I had a Mac and loved it. We raced it in the Biscayne Bay area and won almost everything we entered. It was an early model with just one daggerboard.., and a pretty short one at that.
Our closest competitor was a Condor 40. We would take them downwind, but they would beat us upwind. That was until I replaced the daggerboard with a Formula 40 board, and then it was all Mac.
The first thing we did was redo the gelcoat bottom with epoxy.
They are a bit heavy but it always felt solid, so no gripes there.
Good luck,
Rick