Well, certain aspects of a television's performance are measurable - contrast, brightness, black level, horizontal and vertical resolution, gray scale tracking, etc. With a rear projector, things like geometry come into play (for instance, do straight lines appear straight and not bowed? how much overscan is there? etc.). LCDs and Plasmas won't have problems with geometry. OTOH, a DLP might have better contrast and shadow detail than a given LCD. Until we have some definitive 3D test images and motion video, evaluation of 3D performance on these sets is mainly conjecture.
Rear projection DLP has the edge when it comes to sheer screen size - no doubt about that. For me, that's at least as important as any other factor with 3D. A big screen is important because it pushes the edges of the image further into my periphery. That's where the illusion of the 3D world ends and the real world intrudes. 3D helps me suspend my disbelief better than 2D. The last thing I want is to be smacked back to reality by the hard lines of a television's bezel.
That's not to say that a smaller 3D TV can't provide a satisfying experience. Clearly, it can. I'm just saying that if I had my druthers, I'd always watch 3D on the biggest screen possible. (Of course, I feel the same way about HD and screen size.) My best 3D experience to date in some ways was the 3D film of the space station that I saw years ago at the Smithsonian in Washington. It was an IMAX, wrap-around screen. I got lost in it.
I really don't know what the objective tests have shown about DLP rear projection relative to other types of displays. I'd bet that the bigger screen would easily make up for some deficiencies in other areas. One thing I do know is that I'm going to find out. I helped my sister pick out a Mits rear pro the other day (her first HDTV), and when she's ready I'll help her get set up for 3D on it. I'll be watching quite a bit at her house when that happens.