My friend Justin has three in his SUV hes pushin 800 to each.. He fried his voice coils.. then bought two new ones and pushed the same wattage. sh!t is pretty loud though..
you would need to know if the sub is dual voice coil or single and then know how it is wired. I'm assuming the w3 is a dual 4 ohm and would be wired at 2 ohms.
personally i would have another 500/1 jl amp if it were given to me!!! they always fail. only sometimes to be brought back to life. if you do decide to go with the jl amp it doesn't matter what your ohm load is as long as it falls between 1.5 - 4.0 ohms because this amp puts out the same power at all ohms that fall between 1.5 - 4.0... keep in mind higher ohms put less stress on electrical system and @ 4ohms you get a much nicer sound