I had this prop installed yesterday. Its the best money I've ever spent. I have an O'day 28 and it was repowered with a Yanmar 2GM20f. The original 12" prop was left in place when the motor was changed as best I can tell. Vibration with the 3 bladed prop is effectively NIL. Static RPM is around 3400 and the amount of water I was pushing behind this thing was crazy. I likely could have gone with their original 14x7 vs the 13x7 but I must admit I'm happy right now. I have not had the opportunity to sail and see if I notice any significant drag issues but based on the design of the prop I expect better performance overall. I've also included a picture of what we took off as well as a picture of my new Campbell next the monster going on my father-in-law's 44' CSY.
I highly recommend this prop so far.