Steve, I put some miles on a 24k displacement cutter with twin roller furling headsails. Nothing is better for long downwind runs in big seas. To be effective, the sails need to be large (genny size). You lose the hassle of a main boom banging around and a mainsail blanketing the jib...a problem with big following seas. There normally wasn't a downside to this setup except for the sails banging together when furled. All I did to start upwind work was to furl in one sail and close haul the other. You did have to be carefull when furling up so they didn't get double wrapped (that happend ONCE and it was a major pain to get them undone)...sorta like getting a spinnaker wrapped on the forstay...been there too and it got wrapped so tight I had to cut it off. For non roller furling it would be twin forstays with a sail hanked on each...each sail with it's own halliard, sheets and pole. Twin forstays need to be far enough apart (fore and aft) to keep from banging together and snaps from hitting each other...I really don't think this is something you would do on a 15-17 Montgomery though. In my humble opinion a big genny poled out is the answer to this size boat. Then make sure you have a vang and preventer for the main boom. Storage can be a problem with specialty sails and the genny will do both up and downwind without hanking on other sails. By all means go for a roller furler anyway. Bill P.