Hey folks, I am a newb here, but a friend of mine (punisherofall) asked me to post. Why? Well, I guess since I have both:
56" Samsung DLP 1080P (purchased last week)
50" Sony SXRD (purchased in late January)
Ok, here is my experience description:
 SONY: Well, when I got my first SXRD, it was beautiful, but flawed. Lots of dead pixels, bluish corners on black scenes, and more. I returned it in 48 hours and got another set. This one was really good, could not find any real problems (only 4 dead pixels, stuck in the "gray" position, which were not visible unless you were 12" from the screen). It has been my main set for 5.5 months, and no problems. I calibrated with DVE, and it has looked great. Love the set. Have it plugged into a lower end (HTS 800) monster clean power unit on the power and cable inputs.
 SAMMY: My friend kept telling me about the sammy, how crisp it was, how nice the industrial design of the external case was, and I checked it out, yep, it looked good! I needed another set for the bedroom, so I went and picked it up. Ok, right out of the box, I calibrated with DVE. Hmm, looked ok, but what was that? Ack! I saw what I would describe as "swimmy pixels" even on HD signals (Time Warner Cable HD pakcage, all channels, Austin Texas area). These same signals were clear on my SXRD, so I was pretty miffed. But ok, I had heard that the line conditioners tended to help with mosiquitos on the screen, so I went and got a monster HTS 1600, ran all power and cable connections through it, and voila, perfect picture! Um, oh yeah, I did see freakish rainbow effect my first night with it, on the THX calibration pattern with the white circle in the square box...freaked me out! I don't see it much any more though. Does not bother me on actual video. Mostly saw it when looking at the screen and then quickly looking away (probably catching the color wheel at different colors as the eyes are in the motion of tracking away... your eyes can twitch pretty fast if you make them).
They are both sweet, but truthfully, the DLP is to crisper in my opinion (read OPINION). I love it! Edges seem sharper, and darks are more natural. This is comparing back to back on high quality HD feeds in 1080i, on the same feed, with power scrubbers. Now I am not knocking the SXRD, it looks awesome. But the DLP is just a bit sharper. I have both sets, and honestly prefer the DLP.
Just my dos centavos