Technically, as in the front projector wars, there's no real reason why an LCD RPTV couldn't be as good as a DLP RPTV. Each has their own quirks and advantages. The main problem is, though, is that no one has developed them as much as the latest DLP sets. As far as I know no one makes a HD-Ready one for example. So you have to say that DLP is winning the battle at the moment, largely due simlpy to the absence of a direct LCD competitor.
Personally I'm surprised Sony especially hasn't developed them further, as they have done with front projectors, and they make a range of LCD RPTVs. I'd imagine both Sanyo and Panasonic could make a very decent one if they so chose, too. As pretty much all they are a front projectors built into a cabinet pointing at a mirror and screen.
a sony HD ready lcd r/p and wasn't blown away. The contrast wasn't as good as with a dlp and, well, it may have just been that particular set but there were definite convergence problems, I watched two separate feeds into it and there was a green ghosting to certain dark screen images. However, if this was sorted £1300 from Sony centre seemed like a fair money.