Thanks for resurrecting this thread! I'm still living with the PE7700 (in fact 2 of them, like you, as I had to buy a 2nd-hand one when I couldn't source a bulb anywhere a few years back - really!) and can now replace shattered colour wheels with my eyes shut, almost!
I also need to upgrade at some time but am unsure whether to do that now. I'd like to know how much better the latest raft of pj's are as compared to the PE7700. Has anyone got an honest view on that? Alternatively, I could also hang on for those 4k units!
All the best to everyone here.