I just got off the phone with Valley Engineering, and they said that their 50hp motor turning the larger prop will outperform the 60 hp direct drive vw, and it does so with a pretty significant weigh savings at only 2 gal per hour. Sounds like a good way to clear up some of the those weight and balance concerns featured above. I asked about vibration, and they said as they mount it (metal to metal bead mount) it would be more then a VW and less then a Rotax two stroke. Putting it on rubber mounts makes it very smooth. I guess a bit more gear will be necessary for the larger prop.