About a year ago I bought 2 NP Combat (4.7, 5.6) from a ebay seller based in Florida that brings tons of gear from Hawaii. The sails "look" good in the photos and were describe as B and B+. I paid $160 for each, and I thought I got a good deal. Well, not quite. When I got the 4.7, right away I noticed that the top panel was starting to delaminate, and there were few small tears that I fixed with sail tape. The sail last me 3 sessions before one of the bottom panel teared apart when part of my body land on the sail when I loose my balance. It was not a full speed catapult.
Yesterday, one of the panel of my 5.6 started to detached from the seams by the batten and the mast sleeve, which I reinforced with sail tape. Nevertheless, I expect the sail to disintegrate pretty soon.
I think in the case of these sails, misrepresentation by the seller and bad quality sails were factors with these issues.
I guess it is a classic case of 'you get what you pay for'. The lesson, don't buy rental sails, specially NP from a guy in Florida.

Salt and sun do bad things to sails and NP has not been known to make sails that last. Perform yes, but not last. That's why Ezzy and Sailworks are so popular here in the US-the land of the pragmatic

Btw I'm selling my old 5.8 for 150$ if you are looking for one. 2011 Ka Kult 5.8 in a very decent condition. Otherwise I'll bring to the swap.