Reading with interest as I too am nervous about trying RnR.
I can say though that Everest is awesome. My favourite ride at WDW. I feel like it’s slightly more intense than BTMR, but in a fun way. My feeling is that if you can do Space Mountain, then Everest should be okay.
ToT meanwhile is pretty intense. I still really enjoy it, but for me the backwards feeling of Everest is easier on my stomach than the dropping feeling of ToT.
OP, I would be interested to know if you also tried The Mummy, and if so, how did you find it? My DS wants me to try Rip Rockit as well and I’m quite scared. I’m wondering if The Mummy might be a better compromise?