I don't think there is one perfect ladder that fits every
rib and every application.
Scuba divers can be in rough conditions diving the outside of a pass or reef so the transom of the
rib with a pitching prop is a bit dangerous.
I agree lots of cuts can happen when clambering over the
outboard.
There is also the safe "landing" area inside to consider when in rough conditions.
On one
boat our RIB had a bow ladder and the
anchor rode was transfered to a transome strong point, so the bow became the lee and divers boarded over the bow into an empty space