I went through 2 Vivids and switched to the Nitro. I'm only on my 3rd battery drain/recharge cycle but here are my thoughts so far in terms of comparison to the Vivid:
1. Battery drain does not appear to be that much worse
2. Battery charge time does not appear to be significantly different
3. There is definitely some lag, especially when compared to Vivid. I was FLYING switching apps/screens/etc on the Vivid, but am not near as fast on the LG.
I took my Vivid back because it kept crashing so thought why not give the "new kid" a spin...as well as pick up 30 extra days (returned Vivid to BB, bought Nitro from AT&T) to see how things play out (Nexus/Note available for sale, ICS news for Vivid and Nitro). I do like the screen better on the LG, but net net would consider switching back to the Vivid if nothing else moves as I'm an ADHD kinda guy and the lag on the LG is a bit annoying. Hopefully it goes away, and sounds like a SuperOneClick/hard reset combo maybe offer some resolve. Will post back once I've played around more.