I am a currently practising FO with TFly and happened to be on another VS flight at the same time crossing the Atlantic. At the same point (Greenland) we did encounter moderate turbulence for about 40 minutes, with 2 occasions of serious buffet. Being at the back of a 346 it was certainly wild in places, but on the whole I would expect an average day over the Atlantic. It was not much that a period on oxygen could not fix for most! We only had three passengers down for a short while.
For anyone that cares, I hope this helps.