I use a 700W, so can not speak directly to your WX application but I have had perefectly good service from a US GlobalSat BT-338 Bluetooth Rcvr.
http://www.usglobalsat.com/category.asp?catid=12
I picked it up as a pack with iGuidance software for 170$ and have been satisfied with its performance. As a stand alone recvr it will interface with any software acceptng industry standard data streams.
There will be quirks - you can only use a bluetoooth comm device one at a time; no gps and headset and music and whateverelse you are trying to force the poor thing to do. You need to remember that these phones are very poor at multitasking - they are not desktop computers - they are not designed to run 4 applications at once, no matter what the sales rep tells you.
So much for the soap box.
My gps works great - I use iGuidance in the car, I use GpsDash2 (I dont think this is supported any longer and it is starting to have problems although Handango, etc are still selling it) in the car (not at the same time as iGuide.) and when I run or bike, I use Googlemaps also.