Lee, My 6'0" Austin Twinzer mini-Sim (in avatar) is my go-to board for everything but hurricane surf. If you want to see it or send pics of specific parts, let me know. I've ridden mini-Sims from Hydrodynamica (Joe B.) and Vernor. Joe started off the movement and Vernor makes a quality product, but I think Austin really captured the "planing hull" concept the best out of the three. Just my opinion.
^ +1 ^ This is the only reason why I don't take it out in hurricane waves. I did, however, get it out in solid 8 ft faces and did extremely well with FK-1 keels and Turbo Tunnel side bite Twinzers. Getting back out is a B!%@& at my age, though (43).
if i were to get one, i would probably go with austin too. my sweet potato is 6x23x3 and that is a mofo to duck dive with. lucky it's epoxy and i do not have to worry about squeezing the rails too hard when pushing it under. I am 6'3 215-220lbs and its about 51 liters which i think a bit too big for me. I would probably go with the 5'10 and if i were a better surfer, 5'8. i know the mini and the sp are not the same board but have similiar dims. hopefully this will give something to compare to.