I wasn't in Mosquitoes at the time, but from what I heard the experiment with the square top sail was very successful. The people who tried it out liked it, some claimed it made the boat easier to handle in a strong breeze and it looked good. It wasn't shown to be any faster at that stage, which was another point in it's favour (it wouldn't make the old sails instantly obsolete).
Sadly it didn't become the sail we all use today, but it sounds like that was because in the end a majority were persuaded that it would be bad for the class overall. Many threatened to leave the class if it was adopted.
It's easy to see now (20/20 hindsight!) that those concerns were wrong, as the sail wasn't changed and the class virtually came to a standstill anyway while the Mozzie owners switched to Taipans and sailing became less popular in general. The square top would have served the Mosquito well over the last 12-14 years if we'd had it.
The situation now is a little different. The sail that was being considered then worked ok on the existing mast, but would now look just as out-of-date as the current sail. The square top sail that would be considered these days is more radical than 14 years ago and there's serious doubts that our very lightweight mast will do the job. It will be interesting to see the results of your experiments with the short boom.
The other important thing to remember is that rather than being in crisis control mode, the class is actually growing now. You have to think about what it is about Mosquitos that's attracting people to the class - and be very careful not to mess that up. Right now the Mosquito has some unique features among the catamaran classes (eg. performance for the cost, easiest cat to handle a spinnaker, easy to handle out of the water and fast in everything from a drifter to survival). There's no point blindly making the Mosquito like other catamaran classes if that just makes the Mosquito irrelevant.
I can understand why you guys in SA want to make your Mosquitoes faster, but there is a simpler way, with all the design, testing and research already done for you. It's only a small change, but the next Mosquito you build, use a set of Taipan plans instead.