I don't think there is enough surface area accessible to a buffer on a bike to make it worthwhile. A car, truck or boat is a different story but I put mine on by hand on the bike and it looks great.
I used to think that too, but after using the 3" orbital (right angle) from Griot's Garage with the foam pads, I had my mind changed. On my RG, I could get to probably 75% of the painted areas and at least 50% of the chrome parts with the machine. I got the little 3" hand applicator as well, so you just pull the foam pad off the velcro and stick it on the hand applicator to get to those areas where the machine won't go, then slap it back on the machine and continue. If you "butter" the foam pad with the Glare (I just put some on there and spread it around on the pad with my finger), then put the pad on the surface of the paint BEFORE you turn it on, there is no problem, and turn it off BEFORE picking the pad up off the surface. The variable speeds make it really nice. Of course, when I'm doing this to the bike, I've got the seat off, the bags off, and the side covers off. I've even got a foam ball thing on a 12" shaft that you can put in a drill motor to do the wheels...makes applying the product to the wheels a lot faster. Getting it off is still a PITA though.
But, I'm kinda a gaget head...putting it on by hand works too.