Are you running a bracket of a index class? IMO I would go with a two speed with a slipper clutch and nitro. If running a index class. Being able to adjust the shift point and clutch set up will greatly help. If you are running a heads up or index class it will also help dialing it in. If it is a bracket class then consistantly is what you need. I would think that a brushless motor would be the best set up. It would not be weather dependant. Were as the nitro motor would be. I run index and bracket's I just tune it down for bracket's.