It seems that FM part 15 is pretty useless though based on the range, all the success stories I've heard are AM ones with great antenna setups that managed to go miles...
Part 15 FM is only good for engineered systems, such as controlled radiating coax installations on high school and college campuses. I did an install at a local high school and it works well for covering the campus buildings while maintaining compliance with any off-campus radiation.
Part 15 FM with an antenna is pretty much unusable unless you want to hear yourself on your own property.