Picked up the Knubster for my Rich Price and let me tell you, that thing is freakin awesome. It really does what it says as I had a great chance to put it to the test yesterday through 2 tides, barreling beach break head + and screaming. It really does increase drive without the drag of a tri, although when I look at my fin set up, I'm like holy crap there is a lot of **** there. I have to say that I think its the best of both worlds. With the Knubster the board didnt get too loose off the top like a quad sometimes will and it takes the drift out of the board, the 2 worst traits of a quad in my opinion. I think I might also grovel with just the front fins in and the Knubster, the possibilities are multiplied with this thing. I was given it as a gift from a shaper friend and if you own a 5 box set up, get one.