From what I've read here, it looks like the only noticeable differences are HD size and OTA tuners. Is that right? Any performance or reliability differences? I don't think the larger HD or multiple OTA tuners will matter to me. I called Dish to price an upgrade to HD and when I said I wanted the 722k (newer must be better, right?) the CSR offered the 622 instead. There's no price advantage to me, so maybe they have a warehouse full of them. So, when it comes time to order the stuff, should I insist on a specific model, or just take what comes in the truck?