Bmpcc 4k and frame rates for slomo

Using the bmpcc 4k, when shooting higher speed for slowmotion, would it make more sense to shoot at 48ps and do a further slow down in resolve. Editing in 24fps.
Would this give a smoother slowmotion as 48 is a multiple of 24. And wouldn't it make more sense to have a 72fps option, and could BM do a 72fps option in the 4k

It's not a question of "smoother" slow motion, but of slower or faster slow motion. It's all smooth, using the off-speed function. And there's no need for multiples of 24fps, because an off-speed clip will playback at the project frame rate, whatever it is. It's not interpolating or dropping frames.

The BMPCC 4K can go to 60fps for off-speed, which is pretty slow, for a 24fps timeline. If that's not slow enough, you can go to 120fps in an HD crop, but that can be noisy and prone to artifacts.