Forums (like Digital Spy) are full of complaints about faulty Sky equipment, however, if you had a box that worked fine and has done so for a long time, would you make an effort to let everyone on a forum know about it, the same way in which you would if it was faulty!?
I wouldn't let people complaining on forums about Sky boxes put you off getting Sky HD - I've had it for about a year and would never get rid of it.......and yes, my box has worked fine ever since I got it!