Bottom line for HDTV on the JVC DLA-X70R Home Theater Projector
The picture looks great, so the only potential issue is brightness, assuming you wish to watch with some ambient light present. Assuming that you have put your JVC DLA-X70 or DLA-RS55 in a home theater, or at least a room with good lighting control, there should be no issue. I don't see a problem with a 130" diagonal 16:9 screen for watching football or Discovery-HD, with that good lighting control.
Since the JVC X70 belongs in a theater type room, there should be no problem. That said, the X70 can do fine is a room not optimized, but on a smaller screen, and perhaps (as I had) a high contrast grey screen surface to help with side ambient light.
Very Bottom Line: Works great! Looks great on a wide range of everything that I watch on HDTV, from concerts to sitcoms to sporting events.
Brightness for sports - in my dark surfaced theater: I can have all my rear recessed lights on (7 down facing LED lights - each about 50 watt equivalent), and still find that sports viewing is more than bright enough in 2D, with a fair amount of ambient light in the back of the room. You could easily sit on the couch and read a book, and while gazing up, see a reasonably bright image, with the ambient light having very little effect on the picture. . While there isn't a huge difference in brightness between the JVC X70R's various modes, filling a 96" screen (16:9) even with the lights on, in any of the modes, looks pretty good in my theater. That said, for sports I invariably watched in Stage mode - "brightest", when ever I had the lights on, or allowed some daylight in through my shuttered windows.