I've been having trouble with my HT set up, so I was looking for a replacement unit, too.
All I came up with was a Tivo HD. I found some very interesting tuners but they require a PC to interface with the display/TV. Now, I'm still interested in those because I'd like to build an HTPC but if you don't want an HTPC, then the pickings are slim.
Today, I proved the problems do not lie in my SAMSUNG. I hooked the tuner directly to the display and it synch's up first time and every time. The problem is in my receiver.