Size!
Size, especially beam, with a beam of 7'10" the Macgregor is a skinny boat. If not for the ease and cost of maintenance, storage and trailerability I would choose something longer and wider. Of course that would cost me a lot more so I have to compromise. On the up side, the seasons here in the PNW dictate a seasonal trailerable boat which the Mac is.
Why they didn't go 8'6" of beam which is legal in the majority of locales totally escapes me. It may only be another 8" but one would be amazed at the difference this would make below decks. overall it fits the venue here extremely well but I really would like a bit more room.