MFT have some of the sweetest personalities. I've had mine for 7 years and he is one of the best horses I've known. He will go through anything and has such a personality! And you've got it right- as long as you develop their gaiting muscles and don't let them pace, you can canter as much as you want (trust me, you will want to do it all the time). To develop the muscles you can back them up a hill while you're on the ground, or tickle their belly and get them to raise their back to help strengthen their back muscles. This helps round and tuck their butt under so they gait more smoothly. They are a fun breed to ride and are very willing and sweet.
If you question saddle fitting, just make sure you get one with lots of room at the whithers and shoulder to make room for their shoulder muscles to glide under the saddle. This will help prevent the gait from being choppy and make it easier on your horse.
Enjoy your foxtrotter!!