I avoided Soarin' for YEARS because of my fear of motion sickness. I am very easily sickened on most rides these days. Heck, watching some of my son's X-Box games will induce motion sickness.
Anyway, last year, I was determined to ride FoP (not so much Soarin'). I just decided to get on the ride and close my eyes if it got to a point that I knew my motion sickness would be triggered. I'll be honest, out of fear, I closed my eyes a lot but I ended up doing fine. So I rode FoP again, eyes fully open, never had an issue.
So when our Epcot day came, I knew I was ready for Soarin'. Well, I never had a problem so I rode it twice.
I think you should try it and just be prepared to close your eyes whenever you need to, to see how it goes.