Knight_Errant

One consideration is that MA does smashing damage which is opponents tend to have high resists to. The same could be argued for BS but lethal resists are generally not quite as high.

Overall though speed is the key and BS will dish out far more damage resulting in a quicker "kill". Combine with the knockdown effects of Disembowel and Headsplitter (and a little help from Air superiority) you can pretty much keep your opponent on the floor. If MA has one real advantage over BS it's the cheaper end costs. Even with Stamina and quick recovery a BS scrapper can drain his/her end in relatively short order.

I always thought DM/Regen was a better choice for survival, what with all the hitpoint and endurance buff/recharge effects and a nice dinky def-buff.

I'm not sure with all this slotting of Air Superiority.
I have a 34 BS/Regen scrapper and I use air-sup as an opener in my core attack chain (air-sup, hack, headsplitter).
I only have 1 recharge training enhancement slotted for air-sup and it still works wonders for keeping bosses on the floor while I dice them up. Even without any accuracy enhancements it will still hit as often as my sword attacks which have 2 SO accuracy slots.
If you're a regen scrapper with quick recovery then one end-reduction enhancement is all flight really needs. Unless of course if you really want some speed out of it or air combat durability, then you'll need a lot of extra slots.

Broadsword / Regen is a great combo.
I've got a 27 BS/Regen scrapper and I'm doing fine.
The endurance cost of your primary is almost balanced by Quick Recovery. Stamina appears to be more of a luxury than an essential when you have regen as your secondary.
I know it's cliche but there isn't really a 'right' way to build a BS/Regen scrapper.
EvilGeko's guide for BS/Regen can be found here
It should help you to build a scrapper to fit your taste.