My wife and I have been Echostar Subscribers for about five years. Up until Saturday, we were viewing on two 508 Receivers. We have had no problems with either of them. The twenty-year-old Sony KV-25DXR TV in our MBR died and we replaced it with a 37" Panny Plasma.
We were fortunate in that Dish allowed us, as existing customers, to lease a 942 and it was installed on Saturday. (Dish replaced the LNB's and SW's on my Dish 500 and I did the internal wiring and connections before hand.)
My wife is the principle user of the 942 and I now have
two 508's on my twelve-year-old 53" Sony XBR. (I'm just waiting for it to die so that I can replace it.

)
I wanted to share a couple of items that came up.
1) The 942 was installed inside a glass-fronted cabinet-stand in precisely the same location previously occupied by a 508. Everything was fine for an hour after the Tech left and then the 942 went buggy. (Continuous loop of acquiring satellite, downloading Guide, doing a Diagnostic routine.) I called Dish and the Tech concluded it was likely a cabling issue.
I was fortunate to get the installing Tech back - I had asked for the phone # of his boss so that I could call and tell him how pleased with the professionalism and craftsmanship that the installer had exhibited.)
After checking all wire and connections he and I suspected that over-heating
hopefully was the problem. Re-locating the 942 clear up the problem and no further problem.
2) We experience one instance of sound being out of synch on one of the HD package stations - don't remember which one.
3) Prior to the 942's arrival, I could stand between my kitchen and my living room and hear the sound from two TV's being fed from different 508's. The audio and video were, as expected, in synch with each other. If I do this now, with one TV being fed by either of two 508's and the other being fed by the 942, the sound
on all channels is slightly out of synch. That said, both sets when viewed alone show no sign of video-audio synch problems, so I conclude that there is a very small difference, albeit a
real difference in the audio-video time delay.
Of course when we start using anything new there is a learning curve. My wife has decided to use the 942 in Dual Mode - TV in the MBR and TV2 downstairs in the kitchen. We/she hasn't yet figured how to watch a different channel on TV1 while recording on tuner 1, but we'll get there. (Assuming this is doable.)
We're in our sixties and I haven't heard my wife say "Wow!" in the bedroom so often in years.
Thanks for all the informative posts, they were instrumental in our decision to pursue getting a 942!