Having built cedar strip and radius ply as per Dudley Dixs designs I would not go cedar strip again in a hurry. I know you can get nice hull shapes and have all sorts of other advantages, but if you want a quick build with a good fair result with bugger all fairing and sanding then radius chine ply is the way to go.
As for room inside theres the age old adage of you can have 2 of three things grace, pace or space.
Boat design is all compromise especially when your looking at smallboats, The Didi 26 has similar room to a Nolex 25 and is a lot faster, with more righting moment etc. No