I had a Narwhal 5m rib... it wasn't new - I'd guess just on or over the 10 year old mark.
About 5mins after buying it, the fabric joining the tube to the hull on the port side came off.... cost a fair bit to fix.
About 6 months on, after I discovered other sections coming off, re-glued etc.... whole family out on river, heard a crack, and the starboard side gave which resulted in water pouring in from the bow
Basically, all the stuff I'd fixed was sound (luckily so), but the previous jobs were dodgy. I think the hull was sound, albeit a bit flat towards the back which didn't make a soft ride.
I have no idea what the new Narwhals are like, and have since sold it, and invested in a new Humber.