This matters not to me how you surface swim.
Um, okay.
What works well one place or with one type of scuba rig may or may not work well for another.
Yes. I've actually never seen a rec gear wearing diver doing a *long* surface swim on his/her back--even though I seem to read this often on SB. I've wondered whether choice of gear plays a part. For example, it's conceivable (to me) that if a diver is wearing a very big and heavy single back tank (e.g., a PST 104 or a PST HP 130) and a heavy steel backplate (both of which conceivably would tend to push a prone surface swimmer lower into the water and/or be more uncomfortable, weight-wise, on the diver's back), then that diver might find surface swimming on his/her back much more "efficient" than swimming prone.
Safe Diving,
rx7diver