Hakan,
You are not summerizing my comments correctly.
Secondly, there are too few M20's and M20 GTI's about to make any scientifically sound comparison. Additionally these 20 boats are spaced very far apart and almost never meet. They do at Texel but then you throw out those results that don't suit you. Like this we can go around in circles for ever and I'm not going to that. So lets forget about the M20's
but you have no data to rely on.
But I actually do ! Data gethered from other designs and classes; like the dear old Dart 18 and even the much newer F16's. It is a sign on the wall when adding a jib is enough to make a doublehanded crew just as fast as the singlehanded crew with a uni-rig; IN ALL CONDITIONS. More weight => same performance. I guess that jib must be doing something; like overcoming the hit of carrying 75 additional kg's. Additionally we have all sailed a doublehanded sloop design singlehandedly one time or another. I'm sure you too have sailed your own Hobie 16 sloop as 1-up a few times in the past. Now was that faster then 1-up without the jib or not ?
And if you don't believe me then hook up with an equally skilled friend and do this H16 1-up experiment. Switch boats halveway to make sure that the results are not caused by a difference in sailing skills.
It is sometimes mindblowing how obvious things can be overlooked.
I rest my case.
Wouter