In case anyone else is experiencing the same issue I figured this out, with a little helping hand from the IRC crowd.

I'm associating with an AP that's broadcasting regdomain, hence the linux...

Hi,

I have a problem with the default IEE driver in BT5 R3 for a Rokland n3 (RT2870/RT3070).

If I want to use the 750mW output I can perform:

iw reg set BO
iwconfig wlan0 txpower 28
...