About the experience with these fans....
I installed one on my '98 Roadking because I pulled a trailer fairly often.  
The vibration of the motor caused the fan mounts to break twice.  A redesigned mount was issued, but you couldn't buy it separate from the whple fan.  My dealer managed to get me one somehow, due to the problems I had had with the fan.  (Nothing like a fan breaking loose going down the interstate).  I began to carry zip ties to re-attach the darn thing.
Effective.  Yes, the engine temperature was noticeably cooler, especially in slow traffic conditions, however, at 40,000 miles I still spun a bearing and had to replace the motor.  I might have had to anyway, and I think a cooler engine lasts longer, but its hard to tell if they are worth the money based on my experience.  I have not installed one on my last four bikes and doubt I will on any others, for what its worth.