As for the dealer recommending lower power, he may be basing that on your vehicle.
A lower power amp will clip(reach it's peak, and send a nasty signal) sooner than a high-power unit. This will be harder on the subs.
A high power amp like the 1000w amps I linked need to be used with a beefed-up electrical system. They too will have problems if they don't receive enough power from the vehicles electrical system. Properly installed, these will not fry your subs.
But, just get the JL. It's a solid performer, and you should be pleased
