The points are all well made:
The rudders on the Mac are a real compromise. No doubt, this has more than a little bit to do with the designer contemplating forgetful owners leaving their foils down when motoring at high speed. The consequences of this with full authority rudders would be very nasty.
As noted by many, the boat is not meant as a performance machine (regardless of all that nonsense in the sales pitch), so there is only so much that can be expected in this area.
To get an idea of how significant is the compromise on the Mac, the following picture is from a 16' trailer sailer class that I used to sail:
Notice the substantial rudder stock and the large, balanced blade. These boats would do 13 knots or more on a reach, but you had to have both crew hiking hard to keep the rudder from being overloaded. Now imagine that compared to the foils on the Mac, and the brackets that hold them and you get an idea of how small and light they really are.
Regarding the imprecise steering, that is another issue altogether. I personally don't feel comfortable with the wheel when sailing (particularly racing), nor the way that it promotes the skipper to sit well back.
This is not hard to fix however, and I am currently contemplating a mod that is based on an emergency steering mod in the mods section of this site. I sail in events that are Category 5 & 5N (N for night), the regulations of which now reguire a means to steer in the event of a failure of the primary system.
Basically, all that is required is a pintle (or any surdy pivot) located on the forward face of the transom, just below the engine. A bar will fit over the pintle and will connect at its other end to the underside of the steering bar, where the steering connection bolt goes through it. The bar will have a short extension past the steering bar with two prongs welded to it that have a hole in each, to which I will attach a nice timber curved tiller. I will need to modify the steering bar bolt in a similar way to the motor steering disconnect mod that I have now in order to isolate the wheel steering and pop the pin through the tiller to make that the primary means of steering.