I currently have a CM-7000, Tivax STB-T8, and an Apex DT502; and did have a Zenith DTT900 (LG tuner). I have only a 13" TV with no S-video connection, but the Apex DT502 PQ seems as good to me as those of the CM and Tivax. The Zenith seemed a bit softer and less saturated. I haven't had enough time to switch them out and compare them fully, but I think I may even be seeing less blockyness on dark, low contrast scenes with the Apex than I do with the others.
The Apex guide is very complete. It's postage stamp size, except a little wider and displays listings for 3 programs at a time with the first two lines of description for each visible. When you go to it you just see only the guide - there is no video or audio. You can scroll through the full description for each program and can change channels within the guide. I'm seeing 12 hours of programing info on most channels.
The Apex tuner doesn't seem to pull in signal as well as either the Tivax or CM, but it does display all the channels that the others do.
The Apex DT502 also has an S-video output and a Smart Antenna connector.
I believe the Apex DT502 is still available at Target and possibly also at BestBuy.
Also, You can get the iNet SSR 1921 shipped free if you are using a government coupon from here http://www.ezdtv.com/gallery1.htm
(they don't even require any credit card info). It's a re-badged Tivax STB-T8.