Since this thread seems to be completely hijacked already, let me try to dispel a little bit of confusion regarding air vs. liquid cooling.
First, many people believe a liquid-cooling system can dump more heat than an air-cooled system. But think about it -- ultimately, either system dumps the heat into the airstream. Liquid-cooling systems just do it at the radiator, rather than right at the heat source.
It's also commonly believed that air-cooled systems are more vulnerable than liquid-cooling systems to high ambient temperature conditions, but that's not always true. Light airplane pilots can tell you that often, air-cooled engines perform better in high temperatures than liquid-cooled engines.
In reality, the primary advantage of liquid-cooling systems is that you can bring the heat to the airstream, rather than the other way around. It's easy to design a radiator of whatever size necessary, mount it in an ideal place in the airstream, and pump the heat there using the liquid coolant. This can be a pretty considerable advantage.
A second main advantage of liquid cooling is the ability to thermostat the cooling system. That helps the motor get up to temperature faster, since you're not cooling it until it needs it. That's not especially useful for an electric motor, which doesn't have tight mechanical clearances that perform best when they're kept close to their ideal operating temperature (think sealing a combustion chamber on an ICE).
Of course, the downside of liquid cooling is extra weight, complexity and more failure points. Sometimes the design compromise makes sense, sometimes it doesn't. Obviously, Brammo went one way, Zero went another. Personally, I think the Zero design meets the needs of the vehicle at a lower cost, lower weight, and lower failure rate.