I think you guys are making this way more complicated than it needs to be.

All older designs that add a chute end up with lee helm because there COE was not designed to work with a chute. Some people try to correct for this some by raking the mast waaayyyy back but it can't correct for all of the lee helm.

New boats like the I20 have Neutral helm upwind and downwind because they were designed to balance the helm. They moved the front crossbar forward to balance the boat. The I18 is also designed like this.

However the Hobie Tiger still seems to suffer from lee helm issues. However that lee helm doesn't seem to slow the Tiger down any as it is competitive with any F18.