I just checked this one out and on my PC X64 Cb7.0.4 version (I haven’t upgraded yet!) I changed to 50fps in the prefs, still 60fps in the last slot dropdown. Restarted Cb, 50fps in the prefs, but still 60fps in the dropdown. So I’d say that on PC it’s not working the way you suggest SteveInChicago.
Mike.