Most realiable and easiest to install speed isn't that big of concern but power is... I will be doing some gravel road driving but not many hills. Also someething that maybe in the future I could modify... I realy don't know until I try some things out. This will be my very first build.
From what I've gleaned, the freewheel bearing is the only thing that ever has problems. The remedy is to weld it up after you have probs, or buy the model that comes without it.
I don't see a reason for freewheeling the motor anyway. I had one, and I missed the convenience and safety of engine braking.