I try to tuck the light up under the seat as much as possible. Side mounts are cool too, but more of a cruiser/chopper thing. I don't want to worry about dragging stuff like that in a turn.
Just remeber to use locknuts and tighten everything down good. I was coming to a stop sign the other day and heard an awful screeching sound. First thought was "not my MotherF*#)*in transmission again". I pulled over and some kid in a minivan yells "hey your license plate fell off". The whole damn assembly vibrated off and got sucked up in the rear wheel and stuck between the swingarm. Oops, my bad. Shut up kid.
Anyway, it's rebuilt now...bigger...stronger...faster...and with Locktite.