The hdmi problem can be fixed with the workaround I found:
-set resolution below native
-go to desktops and displays in CCC
- in the small window at the bottom (not the main window) click the corner arrow and go to "configure"
-set overscan to 0% and/or tick the maintain aspect box
-go to 1920x1080 and all is good
I found I also had to go to the basic menu and run the setup wizard for the options to become available, but it worked for me
As for screen sagging, I don't see any whatsoever. as long as the base is on tightly I don't see why it should, as it's a very solid stand.
Oh yeah, I will say that the colours were a bit washed out on the auto setting, but you can easily adjust it to the "graphics" setting which seems nicely set up if you want to avoid fiddling. The buttons aren't ideally placed as they're under the screen slightly, but that's not a main concern of mine as I only used them once.
So far: happy customer
(now to sort out my 5770 issues

)