Hi Bob, you wrote this :

"Like your self, I would like to get the lowest reasonable weight. However after seeing the boat that won the Steeple Chase, I have to admit there is a lot more to the picture than just weight. The SC 20 that won is an absolute beast…something like 550 lbs? "

So I went to the race report, and found some interesting things :
Day 1 : light winds, shifty conditions etc, it`s not abnormal for one boat to extend a massive unassailable lead in these conditions, no discredit to Bill & Eric, but it can happen to anyone (except me. It NEVER bloody well happens to me !). They were also sailing the SC20 "Tall Rig", so I`m assuming that it`s not the standard version of the SC20. Now, all that extra weight they had from 20 years of repairing the boat. as you put it, was compensated for by the Tall Rig.
Day 2 : Conditions were more testing, "around 20 mph out of the south". Now the lighter I-20`s beat the SC20 by 25 minutes, granted they put in a capsize, but it shouldn`t take 25 minutes to right a beach cat (unless it`s really heavy with a tall rig ) so I`m guessing they couldn`t push as hard as the I-20`s before digging the bows in (see pic from the race report).
I have no doubt the Standard SC20 may have even been better suited to conditions on day 2, with a lower aspect rig (perhaps it would have not capsized ?). Now imagine you were to build a SC20 out of epoxy foam sandwich etc & make it as light as a Tornado !
C`mon Bill, just try one !

Cheers
Steve