Keith,
I remember that Tornado in the NE 100... I was sailing the Orange Hobie 18 w/spinnaker that year.
Some of those factors you pointed out might be right. Its tough to tell.
That NE 100 was before the NE style spinnaker came out. Likely they were using the Worrell style spinnaker, the really big one. I used the NE syle spinnaker which was smaller and flatter (no where near as flat as the I-20 chutes though).
I just sold my 6.0 to a guy in Annapolis a few weeks ago. I forget the name of the YC, i'd remember if you told me. It's right on the right after the Bay Bridge. Hes a nice guy but just upgraded from a Prindle 16. He's selling the worrell style spinnaker I gave him and possibly one of the jibs although I advised him not to on ebay.
-Todd