Hi Ralf,
I guess the number of people looking for DVDR'swith DV Outputs is so small that almost no vendor is offering this. However I do have good news for you.
I'm in the market for a DVDR with DV Input AND Output. the reason I want it is exactly the same you need it to. I want to capture in my computer the digital output from the DVD. DVD's I will capture will be flight simulation related, I need to encode them in my computer and the fastest way to do this is if my computer can detect a DV source where to get the video.
THe ONLY DVDR i've seen supporting this is the Pioneer DVR-310-S it is a DVD-R costing around $399 so it now expensive. I plan however to order it it locally (from Circuit City maybe) and make sure I test it first. Just wanted to share this with you so we both can enjoy DVDR's with DV Out for our specific needs.