Adding 70 pounds would be an interesting experiment, but I'd be surprised if it noticeably changes the sailing characteristics of the M15. No new news to you here, I'm sure, but we are much more likely to affect heeling angle by pinching up, easing the main, or simply falling off on a beam reach. I for one was among the first to reef my M15 (I sail an M17 these days and reef sooner rather than later with it as well...) if wind speed warranted. IMO, a reefed Montgomery of any size--especially if you single hand a lot like I do--is much more comfortable to sail in high winds, and you will likely go as fast or faster (if that's your goal in life) because you're flatter. But by all means experiment and report back. It would be a good thing to know... t