TSMM broke down one time when we were in line for it. A 40 min. posted wait time ballooned into 70 min.
I would say always use a FP+ for TSMM. It may be a shorter wait than before, but it's still endlessly popular, in a park with too few attractions (until the new lands open).
By the way, if they stop using the third track in the fall, that would be a pretty disgusting move. Until they added the third track, the wait times for this ride have been ridiculous, all year long. They added capacity in order to remedy that, especially at a time when many attractions are shuttered at DHS. So, having remedied a bad situation, they're going to deliberately give us lousy wait times again? If they try to pull that crap, I would raise hell, and complain to Disney.