I have sailed last IOM Worlds and I have watched last day of M Worlds with inside out + spreader. Outside in gate is somehow dangerous when boats downwind cross boats upwind just after the mark, but it reduces the incidents at windward mark(s) compared with classic spreader. My opinion is to avoid this option if gate is far away and if there is a lot of wind and use usual spreader. If boats are far and fast, you risk hits, and strong ones. Inside out + spreader is maybe the best option to avoid incidents, but : 1/ it's a nightmare for mark layers to get something fair 2/ Boats are so much separated at the beginning of the run that if you are on the wrong side, you are dead... The same without spreaders is easyer for mark layers, but you still have to go around windward boat on the layline before going downwind. So course is somehow shorter for boats not leading. To use Gordon's questions : and comparing with classic spreader Outside in reduce the number of incidents at the windward mark => Yes distribute or concentrate the fleet at the start of the run => Similar allow boats to bail out if they mis-mis-judge the lay line, or which to avoid a congested mark => Yes facilitate the work of the observers and umpires; => You would know, probably easyer as boats are separated facilitate the setting of fair courses. => No Inside out + spreader reduce the number of incidents at the windward mark => Yes distribute or concentrate the fleet at the start of the run; => Distribute (too much) allow boats to bail out if they mis-mis-judge the lay line, or which to avoid a congested mark => Yes facilitate the work of the observers and umpires; => No, more marks to check facilitate the setting of fair courses. => No, worse of all