More current certainly doesn't make an amp brighter, anybody who would write that knows fuck all about this. With everything equal more current will give you better high frequency drive capability into the given load. That means a more stable voltage swing as you push the amp harder.
One of the main issues with Stax is just this, the diaphragm starts to act up as it is capable of pretty amazing frequency response but the amps just can't handle it at full load. Stax "fix" this by dulling sound of the amps to make them a better fit but it sounds like shit that way.