Re: centrifugal clutch
I've used both a regular and centrifugal clutch (the former on my 2 stroke and the latter on my 4 stroke) and I definitely prefer the manual clutch. The only downside is that the manual clutch is not strong enough to accelerate from a stop. Once you get going though, you have more control over how power is being applied to your rear wheel.
For example, I can change how quickly I engage the engine with a manual clutch whereas a centrifugal always engages at about the same rate and at the same engine speed. Centrifugal clutches are also a pain if you like to blip your throttle while coasting down a hill.
It's really up to you though. If you do get the centrifugal clutch, let me know what you think about it.