[sailingfool]

As to the rating question, PHRF NE publishes adjustments info at:
http://www.phrfne.org/adj.htm
These adjustments offer a 9 second credit for an asymmetric without a pole (versus a symmetric), with penalties for use of a pole, and then for length of pole. You should check locally on area practices.

The PHRF NE notes also has a link to some empirical testing of spinnakers:
http://www.ussailing.org/ims/SpinnakerTests.htm
whose results might be described as "...sort of and it depends...".

My bottom line would be one reason you should pay sailmakers like North the big bucks is so that they share their vast experience and give you the best answers to questions like this. Otherwise, shop elsewhere. Barring other conclusive advice, I''d go with the symmetical in a second

Good luck.