3 defece and one end red on both of them and u should be find.
When I started my Stalker, I took Danger Sense. Bad idea. I spent most of my time taking melee hits so the range defense was a waste of time and endurance. I respec'd it out at 25, at which point I took Ninja Reflexes instead, and also brought in Stamina.
With Stamina 3 slotted and Ninja Reflexes slotted with 3 def and 1 end rdx, I really notice the difference. I can have it running almost permanently alongside hide without draining end much. Also combining it with Divine Avalanche makes me completely unhittable.
Since I mostly solo, I wouldn't take Danger Sense back in unless I decide to PvP a bit more - at which point I would imagine it helps a lot against blasters.
Assuming you have Stamina in, it could just be a case of reslotting, and considering how much you really need danger sense.
not only does danger sense help against ranged attacks but its gives you perception to see those stealthy players 
I use claws and ninjitsu (or however its spelled) and tbh I dont see any difference in play whenI use my ninjitsu powers :/
You definitely want both Danger Sense and Ninja Reflexes.
When teaming, if you don't have Danger Sense, you'll notice if you don't manage to get in and AS quick enough, or someone draws ranged aggro, you'll take a hit and won't be hidden any more. Same goes for PvP and any ranged AoEs that happen to come your way.
NR obviously helps when in melee.
3 def and 1 or 2 end rdx in each.
And how you can't notice the difference when they're not running i'll never know unless you don't have any slots. Not slotting means you will get hit...alot.
Once you begin to fill your enhancement slots with DO's and SO's you'll definately begin to notice the difference 
Guys - I really enjoy my claws/ninjitsu stalker, I know that Claws isnt the strongest power but the animations are great when combined with the stalker, stealth image. The only problem I have is that I feel quite cheated with two of the ninjitsu powers, those being Ninja reflexes and Danger sense. I dont feel I really benefit from having them running and they just drain my end! Am I wrong or is a respec due?
Regards