That only happens when there is seat corruption or other seal failure.
The Conquest is so consistent than I had not one problem shooting my old EvoX with a gas thru for months.
Just like any single reg system, there will be a rise in output when the pressure remaining is low...
I didn't see anything remarkable until less than 600ish.
But... with a full fill (or even a less than full fill) of a 68ci, that would shoot WAY more paint than I would carry. A second reg would allow me to shoot it down to the 200's with consistent velocity.