The first thing that will happen if you over power them is popping your spider off - that is easy enough to fix. It is hard to bottom them out or cook them thermally, so I wouldn't worry about either of those too much.
The motor is still quite strong at the suspension limits - this is why I suggested adding epoxy when running over the rated RMS power. That way even if you lock up the suspension hard you won't pull them off to begin with. I'm looking into stronger glue for my next run - as I have burped these with ~800 watts when assembled with epoxy
Before shipment I do test each driver with ~120 watts free air and add a short burst up to 175-200 watts or so to test for mechanical integrity. It will take quite a bit to pull your spider off since they all pass my testing before shipment, but I like to err on the side of caution when advising how to run a driver.