Join Date: Mar 2005
Sportbike: Multistrada 1100S; CBR600RR
Years Riding: Since 2004
How you found us: CRR
The quality vs hardwired will be worse. In theory it all should work fine, but you inevitably get some quality loss at the transmitter. Plus, there will be some degradation from the static, of course.
How bad or good it is - depends on the quality of the FM modulator and your own preference. A lot of people are OK with that level of quality, some just wince and say "never again".
Oh and +1 on the station depending on your location. Just find a frequency that doesn't have anything but static noise, as far as possible from other stations.