Take a 2016 or 2017 if you are of heavier weight.
2015 were soft. Same boards only fine tuning on the connectors during the years.
2016 and 2017 have slight kind of channelling on the tips.
Rode the Carbon NHP 138 split one month ago for two days. I rented it at a kite center because I hadn't my own boards with me. Don't know why they have the split version at a center?......
Very nice and smooth ride. A bit soft for my liking but I weigh around 110kg. Easy and forgiving, very smooth for a carbon board.
Great carving but pop wasn't too fascinating. Holding the edge for big airs was easy though
I have a had several, the 2017 goes together smoother than the 2015,2016. Not a big deal because I would not put it together each day. It just takes a little more work to put them together and take then apart. The 2017 has some different groves and while I think it might ride a little better, it is hard to tell the difference. I have only had the carbon boards but like them. I only weigh 75 kgs.
I just bought the 2017 138 Carbon NHP Split. I havent tried it yet, but I was a bit surprised that it weighs more than any of my other boards I have (5 boards right now in the house). It weighed in at 9.7 lbs with fins, handle, straps...and that will probably be the driest the board will ever be:). My normal board weighs in at 8.5 lbs.
Used my 2016 Carbon NHP split for 10 days straight last month in Brazil. First time I'd ever used it. It was ok. It's the heaviest board I've got/had so not sure of the benefit of the carbon construction other the strength, which is probably similar on the non-carbon. It took plenty of beating without any concern about the split connection.
One thing I hated though was the foot pads. I was having to drop down in the water and take the board off to get some blood back into my feet and the straps weren't particularly tight. My feet were numb after 15 minutes riding. Loosened the straps a few times, to the point I was losing the board pretty easily but still had problems with going numb. Never had that issue with my Axis or Cabrinha boards.