The 340 generally supports 30 milliWatts, while the 350 supports *UP TO* 100mW. The "up to" is defined by governmental standards. Cards for shipment out of the U.S. are set at the factory to conform to the end users regulations. 350's going to Japan, for example, won't do more than 50mW, even though the PHY will do 100mW.
I have no idea what your local power rates are.

Just thought I'd mention it...

Regards,
Hugh