Wouter in the late seventy's early eighty's we released two comercial cats, that were standard with spinnaker and sailed one up. They were the Alpha Omega 4.4 - cat rigged with (opotinal) spinnaker, raced one up (or two) with or without the spinnaker, and the 5metre Alpha Omega raced one up, cat rigged with or without spinnaker, and sloop rigged with or without spinnaker sailed two up.
The problem was back then NO ONE would accept a cat with spinnaker -"spinnakers are only for mono's" and "spinnakers don't work on cats" were the common response to spinnakers on cats.
We also had the Alpha Omega 5.5 m Alpha which was sloop with spinnaker and was usually raced with it's spinnaker, although the spinnaker was derided by most other classes of cats as well as mono's (even though it used to absolutely "kick butt".
Goodall and Boyer had a similar experience when they first put their Taipan on the water (with spinnaker). The spinnaker was dropped real quick, not because of it's performance, but more so by the resistance of the market place.
Darryl