I doubt you'd noticed anything use lens shift, even after reading that it supposedly may cause focus problems, I can't see any. moving my projector into a spot that required zero lens shift was not really possible(unless having the shadow of my head on screen was a more acceptable issue...) and I really don't feel like I'm missing anything. I'm the kind of guy that enjoys a good 'tweak' to try and squeeze some minutely measureable and barely noticeable improvement. I've done a lot of painting, a lot 'calibrating', a lot of tweaking of my screen, and aiming the projector to get a square image. I have not considered remounting my projector to reduce lens shift.
if you SEE issues, fix them. but don't go looking for stuff. there's probably 100 things 'wrong' with your projector, there's a reason it's the cheapest one jvc makes afterall, but none of them will be so glaring as to prevent you from enjoying the movie. I mean, there's probably 100 things 'wrong' with your average commercial theatre too, but you're not very likely to worry about that either
Displays: Samsung PN64F8500/JVC X35
AVR: Pioneer VSX-1130K, 7.1/5.1.2 audio
Sources: HTPC(Enby), PS3, XBOX360, Wii
Control: Harmony One