An active dm or any competent divers would never have any issue with that!I said core skills of a Fundies diver - buoyancy, trim, finning (look, no hands)
They(dm) would not survive long in the trade otherwise.
I have seen plenty of dive guides(with AOW training at most) in SE Asia really impressed me with their all round skills including dealing with OOA situation let alone sharing air with clients. Buoyancy? Even carried couple of extra weights would not affect their gas consumption or finning!