RE: Shockflyer Acc??????
Mike,
It's mostly weight. All the speed controllers for brushless motors seem to be within 10 or 15 bucks of each other dependinng on where you buy. The Castle creations Phoenix series are programmable. Others may be as well. I think the Phoenix 10 is perfect for a shocky and an Axi. The "10" means it will handle 10 amps, which you should never exceed with any reasonable motor on the shockflyer. If you get a higher amp speed controller, the unit will be heavier, as more or bigger transisters are needed to switch the extra current.
If you know you'll go to bigger planes later on, (which will use more current) that is a good reason to get a bigger controller, for a slight increase in weight. Otherwise, keep everythign as light as you can and as light as your wallet will allow.