The point I along with several others was making is that if you plan to regularly sail an area that has a lot of strong currents and long passages between safe harbours, i.e. the lower St.Lawrence River, then you might be happier, and safer, with the more powerful engine.
Now that you have clarified that most of your sailing is going to be on Lake Champlain, although the lake can get nasty, you do not have to worry about the power. There many sheltered areas and lots of marinas on the lake. Because of the smaller engine It may be a little longer getting to a safe haven, but the smaller engine will get you there. As for that one time trip to the St.Lawrence, the boat will be OK. Many boats there have the same kind of power. It does require careful planning because of the tidal range and current, but with preparation of each leg and the proper weather window, it is highly doable.
So, if it was me and I really liked the boat, and if of course it was priced right, I would seriously consider it and possibly make an offer. Conditional to a professional survey of course. If and when comes time to repower, rather than invest in another 9hp I would definitely look at the 2 cylinder engine. Good luck with you decision.