I bought a few I-Opener 2001s at a local CompUSA myself. Sold 3, kept 1, then one of the ones I sold came back (someone actually wanted to use it as an Internet appliance but couldn't because Netpliance has officially ceased offering new service), so now I have two (three including the v2 I-Opener that I'm using this very moment :).
I don't know if the one I-Opener 2001 that I've hacked is just a fluke, but I've had odd problems hacking it. I have yet to successfully swap out the Rise-266 CPU for a Pentium 200 MMX (something that a few people here have had no problems with on actual v5 I-Openers). Also, there are DMA issues that force the internal IDE hard drive to use PIO mode (slooooow).
All in all it's still a cool device, but until I see another person here report positive results trying things that so far I've failed at (i.e. CPU change), I'm going to continue to question how closely these 2001s really are to v5s. Just my $0.02.