RE: Which burshless setup should I get?
More turns = Better efficiency, runs cooler, provides more torque per unit current (better low-end acceleration), runs longer, less RPM so less maintainance.
Less turns = More RPM, faster.
Unless you can get to full throttle on the longest straightaway on your track, you're wasting your time with a more powerful motor. If you're only using 50% of the throttle range, you're losing resolution (control) and efficiency.