oi! agency bashing and I missed it!
The 9m/min ascent rate is viewed by padi as the fastest safe ascent rate, (equal to Alun's mate's rate of exhalation bubbles. The bubbles are the guide should all other equipment fail.) In other words, not any faster than this, but slower is better.
And good to know that some people (janos e.g.) dive more conservatively than the limits given. Why push it?
my $0.02
moray