CVDs are not some magic pixie dust that fix problems. They have their pros and cons, though in my opinion, the pros outnumber the cons. And provided you install and align everything correctly and apply liberal amounts of red loctite, things should hold fine.
I've just come home from a driving session with my Stampede friend, and I've had no problems at all throughout my whole pack (2x760mah 2S). Stampede friend's grub screw came loose again, so I'm inclined to think that it's either a design flaw with Stampede MIP CVDs, or he's using crap loctite.