"That’s what I thought as I have read quite a few people who own these say they routinely put 600 watts through them."
Using speakers with a 600 watt amp, doesn’t mean you are putting 600 watts "through" the speaker. The only way you will put the 600 watts through it, is if you turn it up to 11 and play Ravel’s "Bolero" or AC/DC’s greatest hits.
Your ears will break long before the speakers.
Besides, you don’t get speeding tickets because your car has 600 horsepower. You get a speeding ticket by flooring the accelerator.