I've got the older version, the Samsung SIR-T150. I don't tune UPN that often, as I mainly go to the STB when I'm watching HD programming and go back to cable for regular SD programming. Anyway, I have a occasional problem with pixelation on WMPI and WSRE and those are strong signals. Sometimes it gets very bad and I found that powering down the box for a few seconds clears that up.
The occasional problems can sometimes appear to be related to multipath, as they appear when aircraft are flying over. I'm near Hulbert AFB airfield, so the planes are big, low, and slow (AC130 gunships). The only thing that would help would be a better antenna with a tighter directional reception pattern, or repositioning the antenna.
The fact that some really bad pixelation problems can be cleared up by powering down the STB suggest that the decoder circuits are not perfect. And I'm talking bad pixelation, so bad that sections of several frames of images can be on-screen at the same time, making the image impossible to watch. Luckly, the really bad pixelation is rare and the fix is simple
I can live with it. I would suggest you check the HDTV Hardware area to see if other 160 users in other parts of the country have any problems/fixes for this STB.
All in all, DTV with an antenna is much better than regular TV by antenna in my area. The amount of pixelation/dropouts is very small.
Anyway, welcome to our little reception chit-chat. Be sure to email some of the stations here in the area, it helps to let them know they got a growing population of viewers with HDTV STB. Just this past spring, the engineer at WKRG was quoted as saying there weren't but maybe 10-15 viewers for DTV in this whole area.