Good questions!
I was in on the sailing part of Gaastra, not the designing and prototype stages.
I had to make a finished product work for someone my size, not Pascal's 195+ lbs.
As you know, twist tops came in around those cutaway leech sails showed in '85 or so.
Waddell and North had versions for sale, with bigger wind range...less medium wind punch..than Race or Speeds.
No, twist at that time was not better for everyone all the time. In it's wind range, and no dirty air, YOUR stock Gaastras were faster than most other sails. Props to you!
But, real world racing is done in crowds, not solo.
So wind range is vital. You know Gaastra spec'd soft/med flex top.
By using Serfiac Golds tip extended, which are the softest alu masts of 1985, range was extended, which I realized by late spring '85, on the 3 cam Speed Slaloms.
I told the rep, but he wasn't really interested. I was a novice racer at the time, but had major boardspeed at the time.
86, got Racefoils for racing thru Local program, but got free to use 4.4, 5.0, 5.7, and 6.4 Speedfoils. Turn them in July, get 4 more to use.
Results in speed events were disappointing for sure, but I was 3rd lightweight, at 142 lbs, to Glen McKinley, 175 lbs. I was 2 mph slower.
The unlimited weight class, I would have come in top half, while Glen top 1/4.
I suck at course racing, ok in slalom, so nobody of importance really cared about my mods.
Instead of staying with Gaastra in 89, I went with their partner Rushwind, who said their sails twisted, but didn't and needed the same mods.
Notice Gaastra racing was going downhill quickly by '88. Why do you think that was?

Re emerging with twist top sails in '93...'92's were problamatic, too flat down low even with stiff flex top, then little twist.....the sails were OK, but by then, lost popularity from bad race sails '88 thru '92.
You know that history.