The units are identical - even the part numbers (HD61LPW42). I saw one at my local CC, and it was beautiful. It was right next to the 60" Sony XBR LCD. The colors were better, and the picture was sharp and smooth on the RCA. It just depends on what the settings are, and on the quality of the source feed and connections.
One thing I did notice, was that 2 adjacent mirrors were stuck in the "on" position, and this was really obvious. I've seen a Sammy with one pixel stuck in the "off" position, and this condition isn't as noticeable.
This is a rare problem that can happen with the TI system, it is not related to RCA or any of the manufacturers. In fact, in RCA's case the TI is already installed in the InFocus Light Engine assy when they receive it.