The mylar H16 sails were cut much flatter than the dacron. They fly in 15+ MPH, even at above minimum crew weights, however they are a disaster in light to medium especially with chop. They were only produced for a few years therefore any mylars you find will be 8-10 years old. At that age I would think wear and delamination would effect consideration as racing sails. Dacrons are much more versatile.