Having done similar work (specifically, capturing DirecTiVo and editing out commercials and burning to DVD), here's a few tips:
1. Don't worry too much about "DVD authoring." If a review says it can't author DVDs, it simply means that the included crapware can't author DVDs. All you have to be able to do is capture to a common video format (eg. AVI).
2. Be prepared to spend $$$ on a real video editing software package. I have a dongle that real-time encodes into MPEG2, so I have to use Premiere Pro along with the MPEG plug-in that allows you to edit MPEG files. As a rule, the bundled software is shit.
3. Ditto for DVD authoring.
4. Look for a capture device that will capture to a relatively simple format, i.e. AVI. You'll need scads of HD space, but the end result will look nicer. The aforementioned dongle does a decent job, but I end up having to re-compress the video when exporting the final master, which takes a long time and reduces the picture quality. It looks good enough for my needs, but YMMV.
Nathan