Thanks for the feedback.
One of the things that I'm puzzled about its that a selling point for multi fin boards has been that you can sail a bigger board than a single fin and still get better on-wave performance. Of course the benefits of sailing a floatier board are earlier planning, easier to slog, and ease in getting over whitewater.
But it seems that if I should be looking at the 71 the this is not the case with the quad and that the old sizing rules still apply? This would appear to negate one of the best arguments for multi fins - in my opinion.
Or maybe the 71's actual volume closer to 75 liters? I suspect this may be the case??
I should add that I have not sailed a multi fin board so for me its all a matter of theory and whatever information / misinformation I have gotten on-line.
Thanks again - I really appreciate your honest feedback.