another update, although minor.
After testing with the Boston/Montreal NHL game on OLN, internal 1130 tuner vs rev3 Moto 6412 HDDVD tuner via component, Comcast digital cable as input -- two tuners enter, two tuners leave, although one will be much less popular afterwards
If you have a Rev 3 box, set the 4:3 output to force 480p.(with DVR power off, press menu on DVR remote) I did not expect this at all, but on the Rev3 box, the one with the HDMI port, using force 480p output yeilds a picture very comparable to using the 1130's internal tuner. There are some differences that you will have to decide against (as to whether you want to go cablecard or not..) but in my opinion this config deserves a look. I have decided not to go with a cablecard after testing this setup. I dont think the cablecard would benefit me much picturewise, and with this config, I can still hook up OTA if I want.
If you have a Rev 2 6412, with the DVI port, you should use force 480i for 4:3 content in the setup menu. (with DVR power off, press menu on DVR remote). I couldnt tell a diffence between the internal 1130 tuner (which is what a cablecard would use) and the DVR tuner.
After my experience with the component dvd player in 480i vs 480p, I was under the impression the 1130's 480p processing wasnt all that great, actually quite the contrary, you just have to give it the right input... it may not like that dvd player, but it sure likes the Rev3 6412