Rolf: I sail about 105 kg. Uni, and have a difficult time driving over 15 knots. The spin sets and take downs are tough, but at that weight a heavier puff will stand me on my nose. I must be hyper alert, no margin for error. Conversely, in the 6-8 knot range, I can easily fly a hull down wind*. When that happens the two man (around 150 kg) crews just can't keep up. It isn't skill on my part, just physics.
Sailing uni in heavy air requires extraordinary skill, we mortals spend lots of time swimming. Surely, the very light crews will have the same problem.
*It's very relaxed, nothing I can't recover from.
Sailing uni IS harder, but a bit of practice can help; I'm around 75kg and start to really struggle about about 20kts. BUT I have been sailing uni for about 10 years now!
Itis not just weight!
Sailing single handed is different than with a crew; you need to plan ahead more!