is the problem not far more basic ? Like do you switch to 2G when connected to wifi ? 3 or 3,5G will suck some juice...
Is it the long drive to your office ? When trying to connect to 3/3,5g drains the battery ?

My N9 uses wifi at home and in the office (naturally). I have set my phone to 2G, as I only need 3/3,5G when I am not at home/office and need fast internet.

I noticed this saving of battery power as my N9 was always on 3/3,5G wifi or not...

I always use 2G as I have no 3G in my contract. I set Network mode to "GSM".

I was thinking about using IPTABLES to close the 137,138 & 139 ports, but it's not possible. I probably need open kernel mode or inception to do that.

Ok, I found a way to use the iptables command. I have to login with ssh as user "developer". Tommorow I'll try to block ports 137, 138 and 139 and let you know if it fixed my battery drain problem.

the iptables command didn't fix the problem.
I was happy when I read that PR 1.3 brings WIFI improvements, but the problem still exists in PR 1.3
I'm a little sad. I still like the phone, it does it's job, but not in my office.

The battery drain disappeared after the WiFi routers in our office where replaced, now the phone only uses 9 mAh in idle mode at work.