I have one, 7 yrs old. Had 4 races. I got her as a rescue, from a hunter/jumper stable. I have no clue as to what "training" she had after the track. She is barefoot, does extremely well on the trail, no problem with rocky trails. She had just as soon be in the back of the pack, tends to be lazy, probably why she only had 4 races. He main issue is horse trailers. It took forever to get her in a horsetrailer, and she just shivers when she's in there. She acts like she was in a trailer accident in the past.
She LOVES trail riding. Her ears are up, she's looking around, she is happy. If ridden in the pasture or along the road, she's lethargic, ears back, just not happy.
She is rarely spooked by things.. Only once was it bad. I was riding along the road (in the country) she decided to spook and buck at every car that came by, after an hour of fighting her, I turned around to head home, and less than 100yds from the house, a group of 50+ motorcycles went by, it was too much for her, she reared, went over backwards with me, onto a barbedwire fence, I landed on T-post, luckily just bruised, she ran home. She has been fine since. (I think she was probably in season).
ETA: she is a cribber, so will loose weight when she decides to crib more than eat. Cribbing color doesn't work on her. She filled out nicely, but with her cribbing, she doesn't fill in her top line well. We'll see what happens over the winter. She is on freechoice pasture, and gets a 3qt scoop of 14% pellets a day