[JesseK]

If you go the bevel gear route, you will want as much of the gear reduction after the bevel gearset as possible. This is why you see so many coaxial swerve modules with very large sprockets on the wheel. The higher the reduction before the bevel gearset, the more force there is available to push the bevel gears apart (which they will do by default), ergo the thrust load issues Chris mentions.

The other issue with bevels is that they're relatively less efficient than spur gears at low pitch (bigger, deeper teeth), yet very easily chatter and separate at high pitch when under load (especially on a vibrating platform like a FRC robot or an aerial quadrotor). Spacing & rigid mounting are crucial with higher pitches.