Just checked out the 57" 731 at Ultimate Electronics. I spent 30 minutes comparing it to a 70" Sony Qualia SXRD, and a 61" Samsung HLS-6187. All three of these TV's look very nice running the Mitsu HD feed. The 731 is very bright. Much brighter than the SXRD, and a bit brighter than the already bright Samsung. The SXRD has a bit of a softer picture. This "softness" seems to hide the granularity that you can see in all Microdisplays a bit better than the Samsung and Mitsu. However, it can only be seen if you are standing very close (like 2-3 ft away). They are all very simliar although it seemed that the Samsung had a bit of a sparkles issue. Ive heard this can be calibrated out. Im sold on the Mitsu.
I'm cancelling my powerbuy order for the 6187, and getting the 65" Mitsu 732 when it comes out. Not because the Mitsu blows the samsung away, but I prefer the cabinet of the Mitsu to the Samsung. I really dont thing you can go wrong with any of these sets. Of course, the 70" sony is about 3x the cost at $9999.