It is better to have a lower KV, higher voltage setup as you will end up with a more efficient system. The problem is you are trying to cover an extremely large relative voltage range.

I would expect to maybe get a motor capable of running at 2s and 3s comfortably, but you are asking a lot to have it run safely at 4s too. I would say to get a motor that will be happy to run at 4s all the time, low kv, and just gear it for the speed you want. It makes more sense.

I run my slash 3s all the time. Just geared 19/86 for backyard bashing and geared 26/83 for on road speed kicks.