[nuz69]

The 2200Kv castle is not necessary a truggy motor, in Europe with long tracks it's a buggy motor. No one here take the castle 2650Kv because it overheats in our 1/8 scale buggies on our tracks... Moreover the 2200Kv run more efficient than the 2650Kv anyway...
The 2050Kv tekin is a buggy motor because of its length and its weight. The truggy version is longer and can handle more power. Unless you gear your truggy for 30mph the tekin 2050Kv will probably overheat and run inefficient in a truggy, if you want a tekin take the truggy motor, low Kv and high voltage, like we said earlier : 1350Kv and 6S, geared for 40-45mph should be enough ! 5S 1700Kv will be good too...
Using 6S and 2050Kv will generate heavy current spikes, which will kill your efficiency, even with a low gearing... That's my opinion, the best to do now is to try, I hope you will find your good setup.
Theoritically, you have the same torque whatever your gearing, because the motor compensates the lack of torque with a bigger pinion by pumping more current. Anyway, the higher the gearing you will have, and the longer the acceleration to top speed will be, so strains on the transmission will be equivalent, but longer, so I would say that higher gearing means higher damages to the transmission...