Tried it, took a while, but crashed out again. Had task manager running (for extra funsies); had over 2GB ram untouched, and CPU never cracked 60%, so it doesn't seem (but what do I know) that it's a resource issue.
(*edit. I'm 100% sure it's not a resource issue, as it crashes no matter if I assign anywhere between 3 and 9GB ram to the launcher. The CPU isn't anywhere close to even 60% optimization, so that's out. If I assign less than 3gb ram, it gives the "out of memory" error message, and that's what I'd expect when running FTB and BDCraft.)
Going to try and step my graphics drivers backwards (they were up to date) and see if one of the previous versions creates stability (Radeon 6950, currently 13.9, moving back to 13.4, and so forth).
Probably going to try previous Java versions too.
-- 17 Nov 2013, 00:12 --
Update (since I've seen this problem googled, but not really answered):
The sound files in Minecraft (and Feed the Beast) are causing the conflict. Bizarro.
I removed files OpenAL64.dll and OpenAL32.dll from the folder(s) and I've been online for over 90 minutes, changing biomes, doing work, etc, and no crashes....course, there's no sound either.
Time to find new sound files (as windows7 reports the drivers are current).
-- 18 Nov 2013, 00:53 --
Final update; I got a new version of OpenAL installed; over 10 hours with no crashes, and sound is fully restored.
I hope this helps for future issues!