Thanks for the response. I agree it is a tidy solution to have the clock out mirror the clock in, especially considering that what is being sent to the clock in may not be a steady stream of gates.
Unfortunately I'm stuck in 24ppqn for in and out at the moment as my computers are old, so can't test it out fully. My thought was that you must be generating 24ppqn for the MIDI clock, even when being clocked externally with 1 step per clock. I understand what you're saying about the problem of interpolation, but isn't the device dealing with this already to generate MIDI clock, or does it not send MIDI clock when clocked externally?