Sailing a 140 kg Taipan 5.7 myself (with JIMI), I would say that Wouter's estimate of weight savings seems reasonable. Producing a reliable 20-foot cat lighter than 120 kg may not be worth the effort.

"I won't go into detail at this time, but suffice to say that the ratio of wetted surface area to bouyance (=overall boat weight) does play a factor, as well the ability to hold some momentum when sailing through choppy seas."

This I did not understand (it is not the extrapolation that is difficult). If high momentum was a priority, we would not see the light-weight building that we see in all development classes. And losing weight in the mast, bow and sterns is always desirable in order to cope with waves.

What did you mean by "ratio of wetted surface area to bouyance (=overall boat weight) does play a factor" ?
The distribution of volume/weight is of course important for the boat's behavior in different conditions. Did you mean that reducing overall weight is less important than which parts of the boat which is made lighter?

Stein