All Mtronics run at 1KHz, so motors will whine at that frequency. some more than others. I have not had a problem with it, possibly because I use mounts with a bit of resilience, and there are enough bits and pieces stuck to the inside of the hull to calm down any cabinet resonance.
Alternatives are to look for an ESC that claims a higher frequency, so only passing dogs will be annoyed, or look for a resistive controller and have a nice warm interior to the boat (they work by dissipating surplus power as heat).
Early ESCs ran at the frame frequency (usually 50Hz) and at low speeds growled at that frequency. Again, I never found it a problem, but some did, hence the move to a different way of working when PIC technology became available.