I definately agree with being under way while doing the transfer.
I had a fuel system problem (dirt in fuel) a little while ago, and another rib came help me sort the problem, I had stopped my boat though, and then asked the other boat to come alongside so that he could keep me under control while I tried to sort the problem.
Once we'd realised being along side in rough water was a bad Idea, I panicked and untied the bow rope... BIG mistake... that allowed the boats to swing around and my twin engines clunked with a big a*s jet drive! not good!
however - oddly, I came off relatively unscathed, a scratch on my gel coat, a scratch on the engine and a popped tube. However, was a completely seperate story with the jet drive
My boat clunked the hydrolic ram and bent it
I was thinking about what was said about tying a line around the person first... it would have to be a shortline and tied up close to the bow.. otherwise the person will drag behind the boat, rope get caught in the prop and the person pulled into the prop?