Anyway, what I forgot to say is that, at least for the immediate future (at least a couple of years), I don't foresee any increased towing capacity for the current M-class (nor know of any model year W463s with more capacity); so I went with the upgraded engine in my W460 to make towing (with my present boat) easier -- I'll probably have this boat for at least a couple of more years, and our W460 is now a better match for it.