NS website describes Nordac as woven polyester, is that really the same cloth you mention?
I think so. I bought the sail used and in "excellent" condition; no delam and no mold. It has a "North Sails Cruising Sails" label on it. The tag and the broker said that it was NorDac. My understanding is that NorLam is a racing cloth. I had the sail up for 2 months and mold grew rampantly. Researching the issue, I found that mold grows between the taffeta on each side of the sail and whatever the core is. Regardless, a cruising sail should not get that moldy in 2 months of Chesapeake summer. Unless I'm hard-core racing I will not go with anything except straight dacron.
Fortunately the broker (Bacon Sails), upon my suggestion, applied the price to a new sail and all is well. The new sail is built much better too.