Long time lurker, first time poster. I need help deciding on my first board purchase, and was hoping some experienced guys here would help

I've been tackling the weak Florida surf for two months (2-3x/week) borrowing my roomie's 6'8 board, and am now hooked on surfing. I can catch the wave most of the time now

I'd like to preface this query by saying that despite the aversion to suggesting newbies buy a shortboard, I'll be at the beach three times a week and am adamantly, vehemently, ardently dedicated to getting shortboarding down. Having a lot of skating experience, and some fair body boarding experience, I feel that I'm up to the challenge. Besides, I've done well with a 6'8 board, how bad can a slightly shorter board be?
I'm 18 y/o, 5'10 (177 cm), 130 lbs (59 kg), lanky build.
I seek one thing from the short board: versatility; rather than specialize in any single type of wave, I'd like to be able to go from knee high white wash to way overhead waves sacrificing the least amount of performance.
I already know I want a thruster, standard polyester, shortboard (6'-6'4 height). I'd like to support a local shaper and these are the model galleries of two noted local shapers.
http://www.fluidsurfboards.com/boards/index.html
http://www.tomneilsonshapes.com/boards.php
I'm leaning on the dimensions: 6'2"x19.5"x2.5", with either a Ray (fluid), Amphibian (fluid), Roundo (Neilson), or Superfly (Neilson).
My question:
1. Do I have the right idea regarding the dimensions?
2. Which model would you feel provides the most versatility for covering the everyday Florida surf, the not infrequent trip to more hectic waters in the Caribbean, and visiting my extended family in Cali nearly every vacation.