I had one terrifying experience, where it was blowing hard and I was rather proud of myself for making a perfect pick up, single handed, right in front of the couple on their Hunter next to me. Then the bow came down, the main powered up and Raven started charging for a perfect broad side Tee bone.
Yep. That is exactly what happens if you are not completely depowered when you grab the mooring pendant. I have experienced that very event though not on the FR. It is why, before I sail up to the mooring, I flake out the main halyard (and jib or stays' halyard if one or the other is also hoisted) so it will run free when I drop sails. It is also why I like to have the long snubber leading back to the cockpit. If the FR is still moving too fast I can go around again using the first pass as a gauge. Then, when I have it right, I grab the pendant from the cockpit using a boat hook and hook on with a snap link secured to the end of the snubber or a quick bowline, and then drop the main. For me, this is where having a Tides Marine Strong Track and lazy jacks are very helpful. With the strong track I know the sail will come down like a cannon ball when I let go the main. The sail falls into the lazy jacks. Leaving the helm untended and trying to grab the pendant from the foredeck does not work for me. The mainsheet always snags on something--winch, cleat, tiller, etc.
I also agree with Steve that tight mooring fields are tough. Little room for error. I would not do it on the FR if the wind is too high or the room for error is too small. I'll anchor out and wait till the wind cooperates or the wx moderates. But, I go back to what I mentioned at the top of the other thread on single handed sailing, (http://capedory.org/board/viewtopic.php?f=1&t=35184) you have to know your boat and practice in a wide variety of conditions and don't sail in and execute advanced maneuvers that exceed your skill level. Practice where it is safe and if you foul it up there is no harm done.
It is a very doable maneuver but you have to be skilled, smooth, unhurried, and confident.