The MC30 is round hulled with flatter sections aft so you might call it a semi displacement cat?? I really dont know.
I dont understand why the market should focus on 28-32ft. There is a cat that could match every type of monohull and frankly beat the pants of every one of them in terms of economy, performance and comfort underway. It is quite possible to have very narrow hulls and have 30 knot displacement craft - which are comfortable and seakindly. It is up to the designers and manufacturers to invest in them. Peoples tastes are far too conservative at the moment. We need a major UK builder to build something like the Innovation 52 to really start shifting peoples perceptions. IPS and other engine developments are to be applauded but it is small change compared to the fuel savings that are possible with new hull designs.