Hi Ballaboy,
There seems to be some confusion about the relationship between stability and volume. Volume is not necessarily going to give stability. It depends more on width, rail shape, tail shape and the distribution of the volume along the outline.
The major contributor for stability is width and then how far the width and thickness of the width is carried for and aft of the widest point.
Tail shape also assists in turning and to a lesser extent stability in surfboards, but has a more profound effect in raceboards regarding stability.
Having said all that, it comes back to the old motto "Demo, Demo, Demo" to try and find what you really like.
DM