...one of the experts but i do have a 51/PD 1000/Dish modulator setup. From what I gather (experts correct me please if wrong) all the NEW D-VHS firewire recorders have copy protection potential built in. So the firewire issue will be moot as far as recording goes. The provider will simply black you out of recording when they choose.
I believe however that in a few years all units will use firewire to pass wide band data such as HDTV. My A/V receiver has the potential but no jacks.