The Matrix is a different sort of plane to a DA50, SR22, etc. It has long thin wings which are more efficient at the intended altitude of the pressurised version: FL250.
Unfortunately I don't really get the case for the Matrix; to get the efficiency you will need to be on oxygen, at FL250 lots of it (masks not cannulas, supposedly), and getting an oxygen bottle refilled is virtually impossible when travelling around Europe (as I well know).
The downside of the Matrix airframe is that it has very limited versatility for Europe. Barely suitable for grass, it is a long range tourer.
There is some precedent in partial pressurisation of a fibreglass hull; I believe Lancair have done something on their Experimental models. It would be fun to work out how to keep those gull wing doors shut (never mind sealed) with any pressure differential though
