The only part of Screamin that bothers me is the stop at the end. I swear my brain bounces a round on that one. No there's no way to really brace for it. I have been on coasters with smoother loops, but it's still tolerable, to me.
If you can't do RnR, I would probably skip Screamin'. I was fine on Space Mt at DL and Expedition Everest at DAK but Screamin' put me down for the count! I was so nauseous and dizzy after it. I think it's because it seemed longer. I also seem to do better in the dark where I don't see what's ahead. I feel like because I could see what was going on, motion sickness kicked in more.
As far as Screamin', as others have said...the launch is similar. Except I think the one on RnR goes straight into a loop or corkscrew or something. Screamin' just goes up a hill. It just has the one loop. No corkscrews at all. One bigger drop and a few smaller ones. It's something like 4 minutes long-ish. Whereas RnR is maybe a minute and a half.
Thanks for the responses. Opinion was mixed so I gave it a try. I rode Screamin' with no problems. However, my husband needed to recover after the swinging cars on Mickey's Fun Wheel. I skipped to do a fastpass run.