I'm planning on getting a new Dacron main in Jan, so I'll do the experiment with you.

My current main is a 10 year old dacron, which isn't worth a whole lot anymore. I'm buying dacron, because my crew and I are all pretty new to racing, and we still have plenty of "oops"s. I'm figuring a dacron main will put up with our learning better. Also, we aren't good enough to reap the benefit from the newer materials.

I fully intend to by a new laminate main in a few years, as at least half the other J30s in the Seattle area sail laminate mains already. When I do upgrade, I'll have a practice sail left over, which I wouldn't have for long if I bought a laminate now.