I just got the 138 and rode it first with the crook fins and then without it. I like it better without the crook fins because it still holds a good edge and releases off the top the wake smoother. The crook fins just seem to lock me in too much to the wake so it felt like I was fighting the wake.
Overall, I'm impressed with it. It's slower then I normally like because I have always ridden a continuous rocker but it still has enough speed for my liking, pops well, and lands solid. The swing weight on spins seems good so the board rotates easily.