Re: Overlapping versus Blade headsails which is quicker ?
The spreader length is an interesting point.
On a beamier boat the shroud would presumably hit the deck further out and the spreader would be longer as a result you can't sheet as close inboard. You don't get anywhere near the 10 degree sheeting angle.
So on an older boat(eg a 12metre, contessa, sigma 38 that sort of thing) which is probably not going to be as broad you can get away with the overlapping genoa and still make a good VMG. On a more modern design with a flatter broader hull (TP52, most modern cruiser racers etc) you are going to do better by going for a non overlapping headsail sheeted close to the centre line...
That would definitely explain what I'm see with our Hanse 430.