Boat transfers will never be an acceptable method of transferring folk from rig to ship because they involve basket transfers. Basket transfers are inherently dangerous and terrifying to anyone scared of heights. Personally I have seen two go badly wrong with one guy ending in the sea and the second damaging his leg. He stepped off before the basket was on the deck of the pitching ship, basically he panicked. He had to be returned to the barge that had just dropped him in the same basket.
My company, a major offshore construction company, banned basket transfers years ago and are rarely used. Too many folk get hurt.
BP came up with something called a Frog. The victims would sit inside, strapped in, no windows and were craned from ship to rig. This, as you can imagine, is pretty scary too.
Basket transfers are hugely weather dependent. You can forget a transfer on anything over 30 knots. Helicopters remain the safest method of transferring workers to and from the platforms, rigs and ships in the North Sea.