1. Just remeber the required disk space for recording is approx. 8.7GB per hour.
2. Could be lower, but recommend all things considered, 500+ MHz.
3. AccessDTV emulates TiVO better, but for this you'll need the subscription guide service.
4. Some, but now most are minor bugs. Just make sure you have signal by checking www.titantv.com for broadcasters in your area. If you're using rear projection CRT TV in the mix, highly recommend using the HiPix.
I think it has something to do with the voltage output of the HiPix card being closer to the "correct" levels. Or adjustable to be so. I'm still trying to decide which card to get myself. Or wait for the next generation....