[Tim C]

I have both systems, a Chasing (small piston=less air too) with the PC handle and the Classic with the foot pedal control.
I have the Classic hooked up to my compressor, the Chasing was being run on the HPA tank just so I could answer this question for myself long ago.

I know that the CO2 releases gas as it gets lower and that gives it the long runtime.
When I plugged in the 4,500 psi HPA tank, the control that I had with the air from a tank over that from a compressor, seemed to be better.
I figured I would see how long it ran, except for the issue with leaving it on, I was getting a long, long time out of the HPA tank.

One day I will find out how long it goes, the ease of filling the HPA tank at home from a scuba tank makes it the right system for me. The CO2 is harder to find down here, about every mile, there is a scuba store down here.

Then I will hook up the Classic to both and see what length they get, the CO2 doesn't last long at all on the Classic foot pedal system, that I already know.

I also have a Spider VS3 and the CO2 doesn't last near as long on that either.

It is nice to have a choice, either way, the tanks give the AirGraver systems the ability to go anywhere that you might need them.
I just got some new wheels on my truck that I picked out just so I could engrave them, they have nice flat polished surfaces, oh boy....

Tim C