I did some research and found the Dutchman system
does work with large roach mainsails.

Read Page 10-11
http://www.mvbinfo.com/images/sf_om_a.pdf

For more genearl information:
http://www.mvbinfo.com/dp_02_SF.html


Some industry reviews of the Dutchman system
including opinions of people like Bill Lee.
http://www.mvbinfo.com/dp_03_SF_preferred_by.html