OK, I've got two fishes. A real one (twin fin, huge swallow tail 5'10" X 21 with plywood fins) and a "fish Hybrid" which, in essence, is really a short wide thick thruster (dimensions 6"x20", 2 5/8" thick with a 14.5" nose & 15.5" tail. Both boards have a flat rocker.
The two are quite different. The real fish surfs like a rollerskate. it is fast in a straight line and really, despite all the hype/fashion at the moment isn't that good a surfboard. It's good for stuffing around in crap mushy 1-2 foot waves...and that's about it.
The fish hybrid is a much better board, being wider in the nose & tail than a conventional short-board it's easier to catch waves on that a shortboard, it turns better than the old-school twin-fin fish and tracks better on a wave. I look at the fish hybrid as a real alternative to a mini-mal for an "experienced but out of practice or returning to the sport" sufers like yourself.
Frankly, I find the fish hybrid as easy to catch waves on as a mini-mal, I can get into waves earlier (because of it's higher volume and flat rocker) and on small days my wavecount is the same as my friends on mals. I can surf it aggressively and really get into those 1-3 foot days.
If you want to see what one looks like go to a typical shaper like brucejonessurfboards.com and have a look - you'll get the general idea.
I guess this is where you ask yourself the key question. Are you going to be a sunday surfer looking for an easy surf (the Mal route is best)....or are you coming back as a guy wanting to ride a shortboard...but just one more suitable for your build & weight this time around (the fish-hybird route possibly?
Talk to a local shaper, get a board made for yourself & be HONEST with the guy when ordering about your ability....you'll get a good board that way.