the deal with monos is their ability to tack on a dime without losing momentum. i dont know how that relates to an 18 but what i gave up when i switched to cats was the ability to make multiple tacks to stay in phase and use every windshift. to be honest thats a very sweet attribute of sailboat racing that we catters give away for blazing speed. the only situation in which i lose to the monos is in shifty conditions when they can work every shift, while i forge ahead wondering how long the header will last.