[Al Skierkiewicz]

To clarify,
The restrictions were removed by the GDC in 2012 to allow teams more leeway in their pneumatic designs. The restricting factor is the 1/8" fittings and 0.32cV rules. Inspected for these devices, there should be no serious issues. Large cylinders cannot be moved with any sufficient speed due to the restrictions in volume/air flow.
The pneumatic rules are written such that a single KOP (or equivalent) 1.05 CFM compressor can be used either on board or off board the robot to pressurize storage on the robot. This compressor (either on board or off board) can only be powered by the robot battery under control of the robot Crio and under software control to automatically shut off when the pressure switch is satisfied.

If officials suspect that a robot has been pre-charged with the use of a compressor other than as described above, they can release it's pressure. There are several other remedies in place up to and including disabling, yellow card and red card. Think that a team that uses a method other than that described above is actually taking the field with a robot that has not passed inspection. Check the rules regarding fielding a non-inspected robot for further details.