I can tell you firsthand that when I lived in Tampa back in '98, BGT opened Gwazi and it was SUPER smooth the first few years with the PTC trains. Over the years it became more and more rough until they FINALLY decided (in 2011, I think) to replace them with MF trains and while it was somewhat of an improvement, it by no means made the coaster any more enjoyable. I made the trip back down to BGT in Feb 2014 and it was still running just as rough as it was prior to the MF trains so this (and guest surveys probably) is more than likely why they ended up closing it the following year.
I am optimistic as well for MT and only time will tell but I just don't want MT to have the same fate as Gwazi.