I have owned 3 different plasma TVs, a Phillips and two Pannys. All 3 were wall mounted in smallish rooms that really benefited from the slim profile.

I'm renovating my home and will have a "great room" with the kitchen and family room combined to a larger (25'X25') space. I'm planning on putting the TV in a corner and will have plenty of room for the added depth of a projection unit.

Question: will I be sacrificing image quality by going with a DLP set over a LCD or Plasma? I just started looking and the Mitsubishi (non-diamond) 73" looks pretty good. All of the big box stores have the DLPs in one section and the flat panels in another, so I wasn't able to compare this TV to the flat panels to see if it held it's own. What's the consensus?

Yes definitely. In a large room like that you'll be sorry if you go with a smaller display. Get a DLP, I'm glad I did. Friends that come over to see the game are impressed too.

Each display technology has it's own pros and cons. Thin cabinets aren't the only advantage flat panels have... they also have perfect geometry, something rear projection can't provide. There also doesn't appear to be any DLP sets that offer true 5:5 pulldown for proper cadence on 24fps material. But DLP will typically use less power/inch, and also has a smoother more "film-like" image to my eyes (no noticeable pixel structure).

You can spin the attributes of various technologies any way you want, but in the end, you can get a good picture out of all of them. But what you CAN'T get from flat panels is a "proper" display size for 10'+ viewing distances at a reasonable cost (less than five figures). How it looks from where you sit is what's important, and a 60" display is not going to provide the same experience @ 10'+ as a a good 73" display, no matter how good it measures or looks when scrutinized up close. For that size room, if you can't do FP, then RP is your best bet, IMHO.