German (or Admiralty) style mainsheet systems comes into favor on fractionally rigged performances boats around 35 feet and above.
Up to this point, a gross tune (6:1) / fine tune (24:1) mainsheet system works well. The maintrimmer can play the main 'dinghy style'. But after say around 400 sqr feet, the 6:1 gets hard and the 24:1 gets short.
So.
The German system uses a very long sheet that is run to large (Lewmar 42?) on each side of the cockpit just in front of the traveler. The sheet runs up the side-deck and via a block turn to the gooseneck, down the boom and then down to the traveler via a 2:1.
The mainsheet trimmer sits high side and around the winch, easing the sheet by hand and bringing it it in with the winch handle. Selden now makes a winch that can be eased (backed) by pressing a button on the handle and turning backwards - the winch sheets out. Clever and made for this application!
The First 36.7 has a dinghy style main and that about the biggest boat I would ever want to trim main on while racing. The newer First 35 (same size boat) has the German system and its much easier on the trimmer.
Note this about racing and contrinious trimming. For cruising the difference is not early as important.
Elan E4