Hey all, just chiming in to confirm that I am experiencing these problems as well.
I had ordered a VF472XVT from the VIP Program back in 2009-2010 (either one of those years...can't remember anymore), but ever since receiving the forced firmware update, I have been experiencing the framerate stutter/drop that others here have reported. It is as others have mentioned - it only appears to happen with film content, and does not appear when viewing live events on TV (sports, concerts, or soap operas/talk shows).
Needless to say, it is rather irritating when this framerate drop occurs, as it is random when it happens (usually during a scene transition or when too much movement is happening on screen), and while it can be resolved by simply pausing/unpausing, it's still something that I could certainly do without.
All things considered, I am glad to have stumbled on this thread, as I was seriously worried, thinking that my TV's processor was dying out. Still though, VIZIO needs to man up to this obvious and blatant problem, and address this through a new firmware update that fixes this issue.
Since I have a few DVR recordings to catch up on, I'll see if I can capture a quick video of this framerate drop in action, although I'm not sure how well this problem will appear in a compressed video. We'll see!
ShinBojack - The Host With The Most
XBL Gamertag: ShinBojack