I've never worked with the folks at Maui Fin Co. so I don't know much about that brand.
They seem to get pretty good reviews here on the forums.
I do have some experience with Lessacher design fins.
Wolfgang's fins are what some of the fastest sailors in the world use, so his "orientation" is speed, and that requires good skills to get the board going and small fins to achieve the best speeds.
If you don't have world class skills, I'd take Wolfgang's recommendations and add a about 3 cm.
I sailed one of Wolfgangs Duo Weed 36 cm fins today on the Futura 155 with the new 2008 7.5 m2 Retro. Pretty fast and early planing combo even with very heavy clumps of weed.
The clumps were thick enough that you could feel the drag as the fin passed through them.
Also, you might look at Tekknosport in Germany.
They have good prices and I think Lessacher Design works with them on the design aspects.
Hope this helps,