Hey Rob, funny you should mention it but I have been agonising over this one as well.
I downloaded AKU Shaper software and have been playing with some designs. At first I wanted something about 9' 4" x 27 1/2" but after finding the little Laguna going well in double overhead a few weeks back decided to drop it down to about 9' or 9' 1" as well.
I find the 8' 9" Laguna fine for paddling into the big slabby reef breaks around here but it would be nice to have a bit less tail width and less width in general as well as a touch more rocker. Admittedly this board would be a compromise for the big bombies we get occassionally as a 10'+ would be better for those I reckon. If ya lived in Sth west WA that would be a board you would use a lot!!
Anyways the final dimentions I came up with were a 9'1" x 27 1/4" x 4 1/2" pin tail that came in around 115 litres (similar volume to my Laguna I reckon).
I had to put the extra thickness in to get the volume up a bit as it would have a rolled deck and lower profile rails. The tail and nose are very thinned out as well so majority of thickness is under the balance point for paddling. I am 82/3 kilos BTW.
Anyways it has been fun playing with on a computer so will see what happens. The new PSHs that AA is getting his hands on look sic as well - hanging to demo one. Good luck with it.
PS I will be riding the Laguna for the normal stuff we get around here