After a lot of discussion on this topic about my Kyoto over on electricbike.com forum, I decided to go with a 800 watt, brushless, 48-volt, gear reduction motor driving the left rear wheel via a freewheeled hub/sprocket combo - bmx chain - hub/sprocket mounted on the axle.
The reason being the overall weight of the Kyoto (425+ pounds) we me and my gf on board and a few moderate hills between our house and the nearby bike trail. People over on electric bike guessed that any motor strong enough to get us up those hills would spin the front tire under any significant load.
I'll get some pictures on my set-up in the next day or so and let you know how it works out. By the way the gearing is set to move us at about 20mph at maximum motor rpm and will hopefully give us significant power at 10mph.