If you're going to go smaller you're going to find it more sluggish or really unstable (and hence also sluggis). There is no one shape that does everything but if you want speed and manoeuvrability and stability Blue Planet Bump Surfer is pretty good. www.blueplanetsup.com.au.
Heaps of videos on most models here including SUP Surfing at Torquay on these bigger boards
This is also a great source of information on how to improve your SUPing
Models that I would also recommend from our range are the booster model 10'4 - we have heaps of guys riding good waves on this board and doing some real performance Surfing or the 9'10 turbo which is on the smaller side but will give you a little bit more manoeuvrability but a bit less speed into the wave