They probably would benefit Simos. From something more similar to classic style than they currently use anyway, if still slightly modified for freediving.
But given some can have lousy technique and still perform at WR level while others can train for ages and not get close, it's safe to say it's not a huge factor. Freedivers go so slowly that bad streamlining simply isn't that much of a problem. My biggest DNF dives have been done with deliberately sloppy technique because at that speed relaxation proved more important than form. I can swim with pretty good classic technique in DYN too, but I don't on long swims. Changes a bit as you get faster, of course.
But given some can have lousy technique and still perform at WR level while others can train for ages and not get close, it's safe to say it's not a huge factor. Freedivers go so slowly that bad streamlining simply isn't that much of a problem. My biggest DNF dives have been done with deliberately sloppy technique because at that speed relaxation proved more important than form. I can swim with pretty good classic technique in DYN too, but I don't on long swims. Changes a bit as you get faster, of course.