There are always going to be variables.
Not all amplifiers stating the same power are created equal. Not all users apply that power equally which makes a big difference. Tuning and crossover selection makes a difference in power handling.
But I would begin by taking the WS thermal rating as being correct in a more conservative sense. Not clipped. A regulated amplifier. Correctly tuned/crossover.
Then I wouldn't hesitate to go with 200 to 225 watts in an unregulated amplifier provided all else is managed properly. But that is it. Maximum IMO.
Someone like me, who has a low threshold for distortion and won't tolerate it could run double the thermal rating long term with total reliability. Others cannot.
Compressed or clipped power is far more dangerous because it is far more continuous in nature and creates far more heat. Its not the distortion. Its the power that is the threat. However, a severely distorted/compressed/clipped amplifier can generate a multiple of its rated power.
At some point, dynamic compression sets in. You can pump in more and more power but the output no longer continues to increase by the same ratio. There is no point to it and it is risky for the speaker.
All this really applies to powering any speaker.