I have "plain" Slice X and with it you can duplicate a clip, add a shape layer mask and then use your regular FCP color board controls, with Mocha tracking you should be able to get very close to Resolve for basic tracking for color correction tasks. Of course it adds complexity and possible slowdown on your playback.
Also by watching the sample videos at coremelt, It appears seems to be using Mocha's shape tracking (the shoe tracking for example) not just position. i.e. it will change shape as the object you are tracking changes shape.
If apple would add a few more little icons to the correction: track, b-spline & bezier shape, that would be mighty sweet. In the mean time however, Slice X I think is going allow some amazing things to be done in FCPX.
FYI. I actually started working on a conversion for Mocha tracking data to import into Transform Parameters in FCP via FCPXML. Won't work for Color Correction however, as you can't copy and paste those keyframes from one clip to another.
The Mocha tracking within the NLE is a great time-saver/simplifier. I don't think Apple will add it it natively through. They seem to go spoke and hub with this. X is the hub. Pick your plug ins as needed. Plus, it keeps third party developers engaged with their ecosystem, making $, etc. I think that makes good business sense. And if you don't need higher-end options, you don't have to pay for them. That said, there are still basic functions X lacks that it needs to add in.