Is anyone using these successfully in a high amp draw, high vibration environment? Bought some to build as rx packs for my onroad cars, but everything I seem to be reading from the plane guys that are using these is that they're kind of fragile and experience significant voltage drop under high loads.

I have not had any luck with any aaa receiver pack at present starts laggin bigtime at about 3 min running savox servo's

3 minutes?? You might have a problem with those particular cells. The cars I'm running were made to accept 5 cell AAA packs and at least one current chassis (XRay RX8) can be fitted with a AAA pack.

the chassis i am running is specifically designed to take triple a 5 cell pack i have 3 here 2 new and a used one that a fellow racer gave to me i beleive it is my system is just power hungry but i am running the same radio gear and servos in my nt1 and my gt with 5 cell 2/3aa but those are rated as 1600 packs and those don't have a issue

Savox servos are known to draw a lot of amps..