There are many cnc cutting machines on the market with aluminum gantries....there is very little reflected heat from the process until you get above about 260 Amps. Most air plasma cutters are under 100 Amps.
As far as drives go......plasma works best with acceleration in the 40 miligee range (or better). The majority of plasma cut speeds are under 200 inches per minute, however on very thin sheet materials plasma may require accurate motion at up to 450 inches per minute. Fluid motion is improtant as well....if there is any noticeable "cogging" it will shop up as striations in the cut edge with plasma.
Jim Colt Hypertherm