I'm not qualified to comment on the engineering of the rudder stuck, but it looks good to me considering the size of the rudders. Perhaps I'm naïve.
As for the fixed props, that MUST have been an owner requirement, and I'm quite certain Gregor Tarjan would not spec that on any multihull design he's responsible for. He's a performance oriented guy, and very knowledgeable. If the owner wanted it, I'd bet money there was an attempt from Gregor to dissuade the owner from that decision.
If there was any cat that could be a contender for my next boat, the Alpha 42 would be on my short list... perhaps a few years down the road when there's a used market. Maybe that's coming sooner than expected if someone salvages Hull#1.