Cored or NOT cored?????
I think that a lot of the better builders (and some high production companies like Beneteau and I believe Hunter) have gone to infusion molding. (I believe that the ''I'' in J-Boats ''SCRIMP'' system is for infusion.) This technique has been around for a long time and has been used in all kinds of industrial applications. (Subway seats for example.) My former boat (a Laser 28) was constructed this way and so had almost no liners.
It is a very good method of laying up a hull or deck with a proper resin/fiber ratio. It really is an excellent way to go. It allows more exotic laminates such as kevlar to be incorporated more easy. Properly done it eliminates a lot of labor and results in a boat that does not need liners.
The down side is that it is a comparatively expensive process. The molds are expensive to build since they need to withstand being pressurized. Precision alignment of the parts requires more expensive quality control. Infusion actually uses more resin but less of it ends up in the boat.
Many companies have gone to infusion molding for environmental and worker safety reasons.