If I wanted HHonors points, I would be inclined to go through an intermediary FF program (such as HawaiianMiles) and so end up with 20k points per 10k Amex MR points (the Mileage Conversion Tool at Webflyer will give other conversion possibilities as well) rather than the 13k that a direct conversion will get one.

Amex MR points to PC point conversions have never been a worthwhile use of points IMHO (perhaps with the exception of a special situation such as a quick topoff to pick up a needed stay reward), especially in light of the 1 to 1 conversion ratio that can be had with MR points to several airline mile FF programs.