I own a L800 and received a L920 from work. I actually prefer the L800. I see no compelling reason to move to WP8 at this time. There are few features WP8 has that WP7 doesn't. The few extra features WP8 does have I find utterly unimportant or half-baked. WP7 actually does
a few things better, not to mention WP8's stability problems.
I'd likely feel different if I owned a Gen1 WP7 device, where the performance advantage of WP8 hardware is more pronounced.
As it is now, the main difference is in the promise of WP8... it will improve over time, whereas WP7 will remain pretty much the way it is.
So in conclusion, tell me (besides lock screen apps), why should we upgrade?
You shouldn't. Although many geeks will see incremental improvements to hardware as a valid reason to upgrade, the value proposition of a smartphone is in the software. My recommendation is that you stick with WP7 until you see some must-have app that is exclusive to WP8, or WP8 receives an update that vastly improves its value over WP7.