I've been looking at that product too. There's a couple of really good threads on the AVSForum site you should look at.
I don't really see R5000hd as a true PVR. It seems more geared towards recording of digital content. Basically a really, really good VCR. It sort of does time-shifting, but it appears to be more of a manual process. You can't just sit there with one remote and channel surf and then press pause or rewind, unless your sitting at your computer watching TV. It also looks like to make the product work well, you'll want to have a MyHD card or another third party product for displaying the files it creates on your TV. It does automatically add files to the MyHD file list which would help with time-shifting, but I'm still thinking you have to do the channel flipping at the computer. Given enough time, a guy might be able to come up with a Girder solution to fix the problem though, and MyHD does produce a great picture. Another drawback I've seen is that it only records digital channels. It doesn't have any ability to record the analog channels. As more channels go digital this will become less of a problem though.
All that said, it does seem like a really neat product. I don't think you could ever get a better quality recording, and the files it outputs are accessible and can easily be edited and archived. They also just came out with a new product that doesn't require the HDD200 module for HD content, it works with the 922, 920, or 905, and are giving a $100 discount. For someone just getting into 4dtv like me, this reduces the cost of the R5000HD quit a bit as I wouldn't have to buy the HDD200.
Right now I'm trying a PVR solution with a Hauppauge PVR-350 card and GBPVR, but I'm still very tempted by the Nextcomm solution. Maybe using GBPVR for pausing live TV and R5000hd for recording.