The Mk 14 is one of the very few SP regs that was not really an SP design. In an effort to field a diaphragm reg while they developed the Mk 16 and 18, they briefly marketed the Mk 14.
It's an ok reg and is balanced, but it is not very common and is not in the same performace category as the Mk 16/18 or the evolutionary developments of the Mk 16 and 18 - the Mk 17 and 19.
One oddity is that the seat for the Mk 14 is not included in the annual service kit and has to be obtained separately. The kit and the separate seat in combination are a bit expensive so it is not as cost effective to service as the Mk 16 or Mk 17 for a non-original owner.
On the other hand, it has a swivel turret like the Mk 18 and Mk 19, and neither of those are very common in the US either, so if you want an unsealed diaphragm design with a swivel turret, it is not a bad way to go and is a better performer than a Mk 2.