When I was looking for a decent capture device some years ago I did look at getting a DV camcorder but throwing the idea around on some boards came to the conclusion that a dedicated analogue to/from DV device would be much better than getting a DV camcorder that has passthrough as an added option, for two reasons; a dedicated device would generally have better digitising/compression than a DV camcorder, and if you use the DV camcorder's input/output ports a lot they could get damaged as they're not designed to be in heavy use like a dedicated capture device.

I ended up getting a Canopus ADVC-100 which I've been very happy with, I would have liked to get better hardware that can capture at the same quality but to uncompressed/lossless compressed video but back then high quality capture devices were expensive (I paid £275 for my ADVC-100) and so was the harddrive space needed to deal with hours of uncompressed/lossless compressed video.

I do now have a DV camcorder with DV passthrough but haven't really done any quality tests against my ADVC-100.