If you are afraid of heights and have gone on Soarin, then I think you can definitely do BTMR without a doubt. I am afraid of SOME heights, not all.. but I go on everything in wdw, but if I was really afraid of heights, Soarin might scare me a little even though it is a lot of fun. BTMR doesn't have a drop.. you go up the lift hill (which isn't too high) and you go around a curve. I would suggest that if you are really afraid of heights, maybe sit in the front row because its somewhat of a slower ride because of the small lifts within the ride, the front of the train is already down the little dips while the back is getting pulled more.