I second what COOL said - we used to have problems with reefing line jams at the furler drum. Installed a ratchet block AFT of the cockpit, so the furling line has to make almost a 180 turn - this automatically keeps some tension on the line as you let out the genny. No more fouled furling drum!
The Harken dual-roller jobbies are nice, but if your stanchions are not 1", you have to add spacers (mine are 7/8" - go figure) to make up the difference. Not a big deal, but something to consider. Garhauer is good stuff - worth a look?