MIDI clock sync works great in plenty of apps, it’s just not that well documented in the Core MIDI documentation so some developers haven’t quite managed it. Finger seem to have done it well with BassLine and MoDrum so it shows it can be done. Their apps sync flawlessly. StepPolyArp is also a really good example. It can (and has been) done well.
Having a third party tool for sync’ing may offer a possible workaround for sync’ing apps with one another, but you still need regular old MIDI Clock Sync to sync with external MIDI hardware, nothing is going to get around that.
Looking at how Well Steinberg have implemented other features I to Cubasis I’m sure that if they do implement MIDI clock sync then they will do it well. I just hope it’s on their to-do list??