TSMM is a fun ride. But the big hoopla is about the fact that there are so few rides in DHS. The same ride is at DCA and lines generally stay under an hour because there are plenty of other family rides in that park.
That said, you are unlikely to find a short line without FP, so if you plan to ride it at all, it would be best to use your FP there.
It's best to choose your FPs with consideration to how much time they save you in line as opposed to how great the attraction is.