We had D*. However, to be fair, we had SD equipment in 2007. I think something was horribly done during our installation because when one receiver would be on the other receiver would freeze or go off completely. Then, those two receivers turned green in terms of the guide and display, Needless to say, it felt like a nightmare, and we quickly gave it up once the two year contract was finished. The signal would also go out when it was cloudy; so, I think it was a bad install or really bad equipment. The one thing I did like was the mini guide was not huge when watching a show. The picture on the receivers when they worked correctly was very clear. However, it was more expensive than Dish, and the picture quality is just as good on Dish if not better. The TV2 connections may not have the best picture, but I bet it would be if we had a long enough composite cable to run from the receiver to the TV than just the coax.
My grandmother had an HD setup in 2008 with D*. Her install probably had some error in it; the installers did hers quickly in order to work on some installs for other neighbors who wanted a quick install. Anyway, I noticed when going to her house for a holiday that none of her HD feeds were working anymore, but the SD feeds were. So, a technician was sent to her house that fixed the error and did some cement work around her HD dish. He even admitted that the placement of the coax cables could have been better and that the install did not seem to be the best. After his help, she did not have many issues. The HD TV had a great picture; however, there were sound issues that eventually got fixed. (To be fair, Dish had something similar occur at the beginning of programs which was also later fixed.) The SD TV had lines sometimes when connected to composite cables; I could never seem to get it 100% clear. It was close, though. However, it was so annoying that we could not watch the HD channels on that TV like you could with an HD Duo receiver from Dish. I loved the HD guide that could go a week in advance with listings. However, I disliked you could not chat online with a CSR or with an online team like DIRT.
To sum it up, if you get installers (no offense to the installers out there, but we seemed to have the worst luck) who do a good job, I think all should be fine on the equipment side unless you get faulty receivers or equipment. The HD picture was nice just like Dish's. Those who visited my grandmother loved her Samsung's picture and never noticed a difference when she switched satellite providers. Some of D*'s SD channels like Chiller when we had D* seemed saturated (for lack of a better term) when compared to Dish. D* was more expensive than Dish with our setups of 4 TVs. The base prices seem higher with D*.
I also found while most is the same with channels that there are some differences. Dish has channels that D* did not have like the Epix channels, MoviePlex, IndiePlex, RetroPlex, Sirius XM (which D* dropped in favor of SonicTap), a local channel, and an RSN. I would definitely check locals and RSNs just to be on the safe side and to see which are in HD. D* had channels like TV One, Smithsonian Channel (which Dish once had), Discovery Fit, Disney Junior, and Health that Dish did not offer. I would check the channel lineup cards and compare especially to see which package is best for you and those in your household.
I really hopes that helps. If anything goes wrong, it usually can be fixed with a phone call. If you are thinking that you may be making a "mistake" (for a lack of better term), you could always keep both providers. While that idea is not cost efficient but you would like to try it, I would suggest going down to the Welcome Pack for $19.99/month in case you really hate D*. However, I do not find D* to be completely horrible as some may think I do, but I do find them to be more expensive. Of course, that all depends on setup and what channels you may want especially with the upcoming February increases.