The decisive thing is not the weight, but the _balance_ of the camera/lense. Those brushless motors cannot provide for an arbitrarily large torque to maintain the direction. The ideal balance is, when the camera maintains horizontal orientation without the gimbal being powered on.
The other thing is mechanical blocking. Even though the gimbal is advertised featuring three 360° motors, mounting anything different from a pancake lense will likely introduce a mechanical block, if you really need 360° of rotation about yaw or pitch axis. (Roll should be fine, regardless of lense length).
A variable-length lense (zoom) is likely to add some off-balance to an initially balanced system, once you engage the zoom. Like @VTC, I would strongly discourage from mounting a micro to a "gimbaled" camera, as this off-center weight is likely to compound both mechanical blocking and compensative torque requirements.