I have centrefire in left hand (with left handed stocks) and rimfire in right handed bolt (ambi stocks).
Off quad sticks it makes little difference to me speed wise. Carrying a right handed on the left shoulder I can feel the bolt but on a little rimfire it’s not an issue. Wouldn’t.want it if I were to be spending hours carrying a bigger heavier setup
Maybe if I had stuck to left handers from day one it’d have been better, but I’ve never been minded to change rifle because of the bolt side. As said about they do come up, less often perhaps, but then again sometimes you can get them a touch cheaper if they’ve sat there for a while waiting for the right left handed to come forth!
Long and short - go leftie if possible, but I wouldn’t worry about going right hand bolt on an ambi stock.