This has been a fantastic discussion so far, thanks to everyone for contributing.
It's clear that the jury is out when considering the limits of board length, and wave size.
Watching Keahi's vid of Boiler Point was inspiring. As Keahi pointed out his board is 8' by 27",
but gets a bit wobbly in the chop. Still he seemed to be getting into those 3'ers smoothly enough.
From what I can see, SUP's as short boards are in the early days of invention, and that's what makes
this form of surfing so exciting to me. I'm sure surfers will continue to push the limits of what is possible on these boards.
Just to stir the pot a bit more, I've got a theory regarding taking late drops on a sup. When a short boarder
paddles into a sucky wave, to make the drop you paddle your guts out, and only at the last second do you
attempt to get to your feet. This becomes instinctive with time, as the board falls away from you, your feet
are only just connecting with the board (tippy toes). So once the board finds the bottom of the wave, your body
weight hasn't pushed the nose of the board down, but instead your weight comes down to the back foot, and your
on the wave.
Translate this to SUP, some kind of similar technique would need to be developed, where you remove your weight
from the board as it falls down the face, only to reconnect with your weight pushing down on the back foot,
at the tail of the board. One way this could be done, is to stand as close to the nose of the board as possible
as you paddle, and then jump back when the board starts to drop (I'm writing this with a big grin on my face by the way).
I'm sure it could be done, hey.
What ever, if I can paddle into some nice 3-4'ers I'll be stoked.