Re: Very interesting, advice please
"I have a lot of material in DV AVI format, and a growing amount of material in HDV.I need to capture both formats."
Not a lot of help I'm afraid. Kdenlive should capture a number of formats by firewire including DV AVI & HDV - did you want to use USB ? No real experience as I changed from tape to flash quite a while ago. There were certainly several other programs that would capture via firewire Some people seem to have had success with USB using the program dvgrab which I've also used for firewire which I think is it's default.
http://ubuntuforums.org/showthread.php?t=1138629&page=2