With all of that said - there is a theory that regulators need a certain amount of pressure into a marker to work efficiently.
If you regulate a marker down to 350 psi - but only give it 400 PSI input - in rapid fire situations - you could end up starving the marker. However, on a pump - this is not really an issue.
On the other end - if you regulate the marker to 350 psi but you are giving it 1000 psi input - the regulator has to work very hard to regulate - and thus may not have time in rapid fire situations to fully regulate.
This is all in theory - and in practice I have not seen the difference between my 450 PSI output tanks and my 800 psi output tanks.
However, - were I to be using one tank on multiple markers - I would make sure I had the right input for all of them.