Drew,
The UMHW wheels were from the perspective of "oh hey we need wheels but don't want to spend any significant amount of money on stock" so UMHW was the cheap route taken for the prototype. During the season they would definitely be aluminum, thanks for the warnings we'll be careful using it elsewhere.
M. Mellot,
The pneumatics rules these past two years have relaxed quite a bit (as opposed to other sections of the manual
)
The basic requirements for pistons include,
being rated for >125psi and
"Cylinders may be of any configuration, and may be of any size up to a maximum of 24-inch stroke and 2-inch diameter."
So we're taking advantage of that rule to use a easier to integrate form factor, after all who doesn't like pancakes.