After some interesting times on twinnies, (the San Diego D's and the MR kind) I started to try and compensate for lack of control or sometimes tracking, other times spinning.
The D's went double foiled and felt do-ey , then tried single foiled and they tracked cause of the long base, good for high-lines. Pavel does some good ones and has designed the Carnard Quad for this reason. Rode a good MR twin of Luke Egans, MR would have to have the design worked out. And I believe Akila Aipa's are great. I just wanted more! and to push harder in bigger waves.
Had been having a lot of success with the Sweet Pea quad( like a Carnard), so I moved the MR 78 fin up to 10 1/2 and added 2 small rear fins at 6 1/4, both single foil, ( clustered around where the twin was) with the theory of heaps of drive off the rail with the front big fin and about half the drive from behind, giving a natural squirt release and no tracking. A reversed Larry Mabile Twinzer I guess.
Noosa's Josh Gunthorp rode one before me (a 5'6 x 19 3/4 x 2 3/8) and his first wave said it all. Now Noosa is full of em. The result is The Quartet, good in ALL conditions, I surf faster, carve harder, and get way deeper. Ha! My knees are actually sore from the G's goin' thru carves. No spinning at all. After two years now of constant development, the Quartet has settled into a groove! Enough said!