I have a Staton Honda 35 friction drive on my 1981 Schwinn Cruiser 5 and it works flawlessly (about 600 miles in the last four months). I ride on paved, dry roads here by the beach and with the smallest drive I have decent low end torque and a top speed of 22 mph. In the last 60 days I've been able to ride two Whizzers, a Chinese two stroke and a four stroke Grubee Skyhawk and mine is much a smoother ride. It doesn't have the "soul" of having a engine between your legs but it's a smooth ride, doesn't leak oil and is absolutely dependable.
I have a Staton Subaru 33.5cc friction drive on 2 Micargi Mustang GTS, and a KK GT Dyno roadster. I've road them all for almost a year now with no problems and no oil leaks.They all goe around 30 MPH! It's not intimidation,It's dependability!!!!
These engines are not heavy at all period. The center balance is good. The only small problem that I had was the kickstand holding the bike up when not riding. All of my bikes are friction drive And the original kicks on a couple worked fine,and on a few I had to go to my local bike shop and get a more heavy duty one.[5 to $10.00] A couple of my bikes I used 2 to be on the safe side!