Although my phone is a Desire HD I need to share my experience with you guys.
I have the AirTies RT-204 router and since I started using my phone the battery life when wifi was always on had been horendous (about 5-10% per hour on idle).
However, about 5 days ago my router was restarted and my battery has been excellent from that point on (about 1% even less per hour on idle).
Last night the router has been reset again and the big battery drain has come back again.
What this tells me is that the model of a router is not the culprit for the big battery drain. It has something to do with the IP changing when restarting it. Now, I am not an expert on routers etc but I believe this seems as a logical assumption.
Could some of you having this problem try restarting your router and see if it helps? Remember that maybe it will not have an impact the first time you restart and you will have to do this multiple times.
If u have anyhting more on this please post your thoughts.