Just because of the fact they will only work with Dish Network feeds, I'd pass on these.
Do this; call your installer and tell them you get HD via cable and another OTA box also. How will you incorporate this equipment and will it work? If the answer is anything but "It'll all work", look the other way and don't look back.
Since these are rebadged RCA models I would steer WAY CLEAR of these HDTV's as they are just plain crappy! You can do MUCH better for around the same price and it will work with any manufacturers STB's.
I thought only the DVI connection will work with Dish feeds. The component should work with any feed. If that is the case, I'd go with the 34" direct view. Standard rear projections just don't do much for me. Compare prices at your local retailer. I think 40" rp are less than 34" direct.
From what I heard these are HD TV monitors and do not have the built in tuners for digital channels but I would assume you could use them with any external tuner and the only one I would buy would be the 34" model because I have always had good luck with RCA tube type TV's. I have seen the RCA rear projection HD TV's but I did not like the picture that well.
I have also seen both of them when the Dish HDTV road show came to the LA County Fair back in September. The picture on the RPTV was TERRIBLE. It was poorly focused and dim compared to many others that I have seen elsewhere (although a professional adjustment could help some). The 34" direct-view set was far superior, but still too small to really make a difference in my living room. We sit about 12 feet away from a 10 year old 27" RCA set right now. The 34" wide-screen has a screen height about the same as a 27" 4:3 model. To really appreciate the difference HDTV makes I would need something much larger - 50" or so. Considering that you can get a 34" CRT set at Costco for under $1000 and a new 811 from Dish for $149 or $199 neither one seems to me to be a good deal.