Just a couple comments on things I've seen in this thread.
DVA gets its guide data from the same place the replays do. In NO WAY does DVA "push" its guide data into the replay (in the situation where DVA has data and the replays do not).
Regarding the DHCP bug... With any router I've dealt with, I haven't had issues with 1) let the Replay get a DHCP'd address. 2) change the Replay to manual settings identical to what was DHCP'd, except change both DNSs to the WiRNS box. When the replay stupidly asks for an IP address, it will get the one the router originally gave to it, however since the OS has the manual settings (with the same IP address, mind you) it works. I happen to have a Cisco which lets me give different devices different settings (DNS included). Way cool. Changing to a data card and a cradlepoint router if it ever quits being backordered--jury is still out on that one.
Regarding WiRNS and the electricity it takes, etc. First, come on, turn on a computer for overnight every few days costs too much money? In that case the replays cost too much too. Do you eat only bread and water?
That aside, how about a virtual XP box on your mac. If the mac is on all the time then it'll take a fraction of the CPU to run an almost-idle virtualized XP with WiRNS on it. If not, the mac needs to be turned on overnight every few days, just like a PC would.
I have often wondered about an off-site WiRNS server. Then I could run one computer for multiple family members or someone here could run one for the setup-challenged people or some such. Seems possible, but I don't have a fixed IP, so it would be pretty difficult. I can't put in a dynamic DNS name for my DNS settings. =) The place it would be useful for me is my grandma's place. My parents stay there a month a year, there isn't a desktop around and maintaining wirns on it would suck anyway just like it would on the laptop they bring. Not sure what I'm going to do there.....