As of 5pm tonight, I have replaced a 508 with a 721. I have not had a lot of time on the 721, but it did take a while to come up the first time and I had some remote issues. It felt like I was kickign starting it. I think the problem was mainly I was not patient enough to let the box initialize itself. THe Font size is a lot smaller than the 508 so if you have bad eyes, keep your 508. I do like the overall look better and the PIP and 2nd tuner is going to help a lot for me.. Give me a few days and I will have a better opinion. Going to have to see if I can find those checkboxes.. The info on the Guide is a welcome addition too. Buttons are much smaller. Overall I am glad I ran the 2nd cable. I would not put a lot of weight to Applieds issues. I had similar problems, but it was out of the box experience and it was with older software 1.19 that I had mine. Be intersting what Applieds thoughts are one week later after the box has settled in.