Just tried out a weed model of the "Maui ultra fins" and found that it does hang on instead of spinning out. (I have a tendency to be a bit heavy on the back foot). The fin was a 32cm weed coupled to a 118 jp super sport with a Ka koncept in not over-powered conditions.
When the fin arrived from Hawaii I noticed it was a reboxed tuttle. The material used to rebox was white and you could clearly see through it to the twin screw bases. My immediate thought was I'd paid full price for the fin and it did'nt adhere to what was advertised.(grey area). Call me pedantic but when I bought an "mfc" it fit in the box with no protrusions that would cause cavitation!! This fin however sat up proud of the box by about 2 to 3 mm in places which had to be sanded back to fit the box. The foil itself was great and I'd be interested to hear if anyone has tried these out in the tuttle format. (unaltered/adulterated)
In conclusion, I have to admit to being told not to sail over a certain part of the area we were yesterday. I was thinking "now where was it Mike said to stay away from???", bang. This must be it!! Result; one brand new demolished fin.
This fin will now be consigned to the remodelling department. Possibly a 27cm speedie. I just happen to know someone who is off the water at the 'mo.
Don't get me wrong, this is definitely not a spray at "Maui ultra fins" and I''m sure that the fins live up to their advertised specs, but before purchasing one I would make sure that the fin was not reboxed.
Bummer about wrecking it.
I've been thinking about getting one of their wave fins to replace the fin that came with my jp 92L fsw pro edition, its too big, yet likes to spin out 
. Have been waiting for the aussie dollar to climb a bit more against the usd... and i tend to ding my fins pretty rapidly too, so maybe its not worth it lol. A lot of the top pro's seem to be using their fins thou, so I want to give them a try.
i'm real keen to see what the xwave is like also.
i like the idea of an upright wave fin, 
it bothers me though some of the things written on the website. i don't want to appear like i'm bagging the fins as i have never used them but -
the constant references on the MUfins website about their fins not spinning out and the suggestion that, that's what makes them superior doesn't hold water with me.
none of my MFC fins or C3 fins spin out.
the other thing that i'm not sure about is that i've never found upright fins to turn as well as wave fins.
i'm hoping there will be an upwind performance advantage.
