The verdict is in, and it doesn't look like much changes for people who take the buy back check, my car is worth 21k including the settlement portion which is slightly over 5k.
What has changed is an option for trade in, which directly impacts my sitch, I'll get 'current fair market value' to be applied to the trade (approx 8-10k) which saves me the tax, approx another 1k. The difference between settlement + buyback price and trade in portion is issued as a check and can be applied to the trade but doesn't reduce the tax owing.
All in, 53k-22k leaves me with a loan of 31k canacukian ruples which is 23k in real dollars and nothing out of pocket. That's still a steep three year pay off monthly but interest is really low. I may consider stretching it to 4 yrs and take a 0.5% penalty.