If you have a fixed or "SMART" antenna, want a "FULL" EPG (2 weeks +), and could use S-Video try the DT502.
If you need "TIMERS" (the DT502 has reminders) and don't mind "Next/Now" EPG with no description (Zinwells biggest drawback), get the ZAT-970A.
Reception wise, they both perform the same for me. They both treat "Parental Control" the same and they both have "Recall" buttons. I like the "Favorites" grouping of the ZAT-970A, although I like the "Favorites" UP and DOWN buttons on the DT502. The DT502 has an internal power supply and a metal case, while the ZAT-970A uses a brick and has a plastic case. I consider the remotes for both units, "TOP NOTCH."
I'm on the verge of tossing my Insignia -APT, since I now have multiples of the DT502, ZAT-970A, and Sunkey SK-801ATSC. Keeps me from having remote conflicts.
Checkout my comparison link below.