Giovanni, that's a rather broad stroke to brush the motors with
The Kv required depends on many factors, as a note the bow thrusters in my 1/48 scale FFG are 11000 Kv
A brush-less motor is purely a motor that is electronically commutated, IE the ESC takes on the roll of the brushes, there are many ways to skin a cat, gearing can still be a useful addition to obtain high torque in a small package.
Someone mentioned that the reversing controllers had more components and therefore more expensive, this is not true, the ESC's are essentially identical in the arrangement of the switching components, the programming is different, the program just tells in which order to energise the windings, that's why its so simple to reverse the motors all that's happening is the order of windings energised is changed.
Biggest advantage of brush-less motors for me is the much wider range of motors within a size range that have different Kv ranges and the fact that all these motors are labelled with ratings that make sense
instead of speed 600 7.2 volt which does not give any useful information other than it has a nominal rating of 7.2 volts, no clue to its speed ?
Cheers
Nick