I have a rather large center channel speaker that is 26" wide, but is rather portly at 80 lbs. Currently I have it on top of 32" CRT phillips, but looking down the road for a RPTV. I *really* like the 50" Sony. BUt I was wondering if there are any that are better suited to supporting (just the front edge of the speaker, I will have to make a custom shelf for anything I get that would more than likely have legs that go down the back to the top of the TV stand) such a heavy center channel speaker.
Should I be looking at maybe an LCD unit instead?

I think you should be looking at some other means of supporting the speaker. I wouldn't place even the front edge of an 80lb speaker on the top of any set, rp or lcd flat panel.

A simple solution is to purchase a tv stand with enough space on the shelf below the tv to place the speaker, and put something under the front edge of the speaker to angle it upwards a bit.