Thanks for the last few awesome replies guys. I've done a lot more researching while getting feedback from here... It does sound like the reliability all comes down to the tranny hooked up to the HuaSheng unit.
So should I be looking at this for reliability and ability to endure some miles?
49cc 4G T Belt Drive Complete Gas Powered Engine Kit - $379.99
^Isn't that the same kit as the one on gasbike.net? Also, if I were to go with the above kit from bicycle-engines, what drivetrain do you guys recommend?
"Choose from either the 80 tooth main flywheel with one way bearing and 10 tooth solid drive sprocket OR 100 tooth solid flywheel with 12 tooth freewheel sprocket."
Thanks for all the help!