Hard to say without actually trying it. PCB's are usually cut with a shear. For the price it's worth a try. If I were you I would be careful not to breath the dust from the cutting.
I would go for the diamond blade, milling fiberglas wears out carbide endmills (carbide does last much longer then the "steel" mills) besides the diamond as stated could also be used for tiles...
It will work for tiles and glass, but I bet it will not work at all for PCBs. These tile cutters work by making a stress line in the tile which then becomes the point where the tile breaks.
PCBs are made from fiberglass cloth impregnated with resin, so even though the top leayer might crack right, the rest will just tear and leave hanging threads of fiberglass.