[johntm]

While I understand that thicker plates require more amperage to cut (in general), is there an advantage to cutting with a higher amperage than the minimum required? I know 40A will cut 3/16 AL plate, but does the cut quality improve with 60A or even 80A?

Yep, you lose more material to the kerf at higher settings, but can you cut a cleaner edge with less nozzle damage at 80 vs. 40?

[carbidecraters]

Yes you gain speed when you use higher amperage and are less likely to spread the heat. The same rule applies to laser cutting. The higher amperage and speed is used on sheetmetal so it doesnt start to walk and bend.