Risk using amp Wattage than speaker rating?

1) How big is your room and 2) from your listening position, how loud (in dB)do you like to listen most of the time?

I have not had any problems exceeding the suggested wattage range. Pushing them hard means playing them loudly with a distorted signal from the power amp or section of an inregrated/receiver. It is the distortion or clipping that blows your speaker. In many cases having an under powered amp is the reason that a speaker blows. The reason for that is that the small output amp strains when trying to get to the desired volume, that straining pushes the amp into clipping and sending a distorted or irregular wave form to the speakers. So the bottom line is not to drive your speakers with distortion, powerful will likely distort at higher volume than a small amp will.
All that said it is of course possible to exceed the speaker's ability to fill the room at the volume you desire. You can blow the drivers simply by sending a more powerful signal than they can deal with. I don't know if your speakers have a very limited maximum output in terms of Db, and thus the stern warning from the manufacturer. A Db meter can be bought at Radio Shack, they are inexpensive. Never the less the most dangerous and most likely problem remains distortion IMO.

Exactly. And when that distortion is being caused by an over driven amp, it's going to be excessive heat that literally "fries" your drivers. Mechans is dead on. Unlimited power eliminates this factor from the scenario. I would definitely not use a classical cd to see how far I could go with my speakers, but buzzing due to over driven speakers versus buzzing due to an over driven amp is way less dangerous. Just turn down the volume and be reasonable.