3A is heaps - The linked page shows a 1k resistor to limit the current. 1k at 12V is only 12mA. If it really draws 3A, something is wrong. By the same token if one of those switches lasts at 3A I'd be surprised.

However the switch you linked to is momentary. It would only work as long as you held the switch. You would want a push on/push off switch I think.