HDTV receivers. Does it matter?

I don't have any real experience in this regard, but I have heard that there can be serious compatability issues when mixing brands.

They are not all the same. Although, I gather some of the innards are OEM'd--I think the Sony and the Zenith, for example, share insides. When I was looking, I thought the consensus on www.avsforum.com (wackos as serious about video as a'gon users are about audio) was that Zenith's box was one of the best.

I have RCA DTC-100 and Samsung STR-150. I hope I have the model # right?
They both ara connected to same outdoor antenna here in Los Angeles and both give great picture on My Toshiba and Pioneer HDTV. From this experience, I have to say one is paying for
features more than quality.
I use for O.T.A. stations only.

of course they have different picture and sound qualities. The dish network 6000 picture quality is inferior to the direct TV high definition receivers IMO. the 6000 lacks some clarity.

I don't think that there are major differences in the picture quality of the HD boxes, but you cannot compare DirecTV's HD against Dish's HD because the differences is likely the compression from the sat company instead of the hardware. You would only be able to compare each via OTA stations. From what I gather, there are a couple of units that have had some bugs, but I don't know which off the top of my head still have them and which have been fixed.

AVS is definitely the place to check out for this answer. They think people are crazy to spend $250 for an audio interconnect, but have no problem spending $250 for a video cable...

Mostly, I would look at what features you need, such as VGA/RGBHV, Component, DVI, Firewire, if it has an RF remote (if you need one) or some other feature. Once you get through that, you may not have much of a choice left...