If you are not going to take any of the leadership pool powers or one of a high drain use such as Telekinesis then... yes, it is possible through careful slotting and IO sets to claw back some endurance.
I'm not sure how useful you'd be under pressure in a PvP situation or an AV/GM fight... but its possible.
If you are taking any of the leadership toggle powers...
I wouldn't recommend it.
I suppose what you are aiming for being useful at? - PvE? - PvP? - a hybrid of both?.
Personally I find Stamina Invaluable even though I do not have the leadership pool and even though through the latest sets I have respec'd down the number of slots - It still makes a marked difference in my opinion.
PvP you need Stamina. For PvE, I'd mostly say the same since ED as you can't get near perma RA (unless you go for some crazy +Rech build but hey).
It may be easier to handle if you go Power APP and grab Conserve, use that when you run low and RA's not up.
Well call me Braggy McBrag, but I got my Emp Def to 50 very comfortably without Stamina, so it is possible.
I also had three of the leadership powers toggled on (albeit slotted with 3 x End redux each).
With Hasten and the End Mod aura I was mostly alright. Although I will admit that in a prolonged battle it could be a bit of a struggle.
In my opinion is was not worth using the three power slots to rectify this minor inconvenience although I do appreciate others may strive for the perfect build.
The choice is yours.
As already mentioned, it's fine although you might struggle in long battles if you have expensive toggles running or fire off your attacks a lot.
If things get tough, ask the rest of the team if they wouldn't mind taking more damage. You can help this by stubbornly refusing to use fortify or to heal them above half health. In this way, you should be running on a decent amount of vigilance. Which is nice.
DON'T eat muffins while I'm developing you.
Pants! Turkey Magnates! A man in a box! Rogue AI! Come one, come all, to arc ID 10107 - It's [i]'Not as long as some other arcs'[/i]!
I'd say no even in pve you want to be running ss so you can run and heal diffrent people when they are spread out, which happens a lot
Ok, I admit I am speaking from a position or relative ignorance here as neither of my defenders (one an empath) is above level 20 as I have focussed on other toons.
The though that occurs to me tho is that, if you play pretty much perma on teams then Endurance should never be a problem for a defender because of their inherant.
I still remember from my earliest days, being on a tream with an empath who was chucking out heals and buffs like mad and beinf amazed at how their end bar never even blipped! It was only then that I learned about the defender inherant power.
[ QUOTE ]
Ok, I admit I am speaking from a position or relative ignorance here as neither of my defenders (one an empath) is above level 20 as I have focussed on other toons.
The though that occurs to me tho is that, if you play pretty much perma on teams then Endurance should never be a problem for a defender because of their inherant.
I still remember from my earliest days, being on a tream with an empath who was chucking out heals and buffs like mad and beinf amazed at how their end bar never even blipped! It was only then that I learned about the defender inherant power.
[/ QUOTE ]
This is sort of what I noticed to with a low level emp and which made me wonder. Still it is possible that the laster level Buff are more end heavy than the lower level heals so that you need stam for them.
I've started playing a new empath and am deliberatly going stamina-less to see how possible it is and I admit I'm only level 24 so far so perhaps not really into the heights where I might start noticing the need for stamina...
However, by slotting IO sets I am getting a good balance of end redux in my powers as well as recharge and heal etc and so far I've not thought ooh wish I had stamina at all. The power I've missed most is swift as it takes me just a few seconds longer to catch up with unruly team members that have decided they want to be a hero 
I think it could be possible personally and I'd say try it. You can always respec later if it goes badly wrong
Its 100% possible but unruly teams is something to avoid. Being that unruly teams are impossible to avoid..give up now! 
He will honor his words; he will definitely carry out his actions. What he promises he will fulfill. He does not care about his bodily self, putting his life and death aside to come forward for another's troubled besiegement. He does not boast about his ability, or shamelessly extol his own virtues. - Sima Qian.
I have a level 44 Mind/Empathy controller... staminaless.
Absolutely no problem, and I tell you... I am constantly spamming powers from my primary and secondary: AoE holds, ST attack chain (dominate-levitate-mesmerize-psionic blast), buffs (clear mind, fortitude, adrenalin boost) and heals...
The only time that I find myself in trouble is if I forget to toggle off fly and toggle on hover. My endurance bar begins to plummet down.
If you want to go stamina-less, some things to have in mind:
- Toggle-light build. So, better without leadership.
- IO set slotting is your friend, most sets have nice end reduction components. Having 30-40% end reduction is pretty easy... and nearly unavoidable.
- As a defender, you'll have Recovery Aura from level 18 on. That can be up quite often (about half of the time). 400 sec. recharge, that goes down to 205 sec with three recharges... and even less with hasten and some +recharge set bonuses. So, in the end, pretty much 90 seconds it is up and 90-95 seconds it is down.
- Kinetics are very popular nowadays. You will probably be speed-boosted (so +end recovery) in teams.
- Eating blue inspirations is not a sin.
- You always can plan a build with Stamina for some time and respec it out at some point to get other powers, when you have your IO slotting sorted. That moment is always very good for me, because I gain 3 new shiny "active" powers in one go. 
Hmm I could say an empath is viable without stamina, but a mind/emp is kinda hairy if you ask me. You would only afford tk when RA is on, and keeping a big team comstantly buffed would ruin you end in seconds, let alone heals in tight teams, control powers and some toggles on like epic shield
[ QUOTE ]
Hmm I could say an empath is viable without stamina, but a mind/emp is kinda hairy if you ask me. You would only afford tk when RA is on, and keeping a big team comstantly buffed would ruin you end in seconds, let alone heals in tight teams, control powers and some toggles on like epic shield
[/ QUOTE ]
Do not have TK and plan to take my epic armor at 49... not that it is of any use to a squishy controller. I rely on controlling my oponents for damage mitigation.
I buff the whole team all the time. I use AB, fort, CM and the auras every time they are up. Well, I do not CM the toughies, for example, because that is unuseful most of the time. Anyway, the OP, as a defender, has access to vigilance, so he will have even less problems with stamina than I do... and I don't have any.
You are welcome to team with me and see for yourself.
I really REALLy insist, than a staminaless empath is viable, except if he wants to run many toggles, like all Leadership pool, or attack heavily (which empaths rarely do). 
My Mind/Emp has leaderships, mind over body and has super speed always on and the cost of it all is possibly roughly equal to stamina with her slotting.
My Empath/Psi is almost exactly the same though.
He will honor his words; he will definitely carry out his actions. What he promises he will fulfill. He does not care about his bodily self, putting his life and death aside to come forward for another's troubled besiegement. He does not boast about his ability, or shamelessly extol his own virtues. - Sima Qian.
It probably is possible but how usefull is it?