If you want to go w/ 3 amps MTX has some great ones which push out plenty of power, are small and you can find them for pretty cheap.......they're great amps or u can do single 1501D mtx
Total RMS on those three subs is 1200 watts, so the 1000/1 would be fine. If jl recommends a 250/1 or 500/1 for one 10 then the 1000/1 should be fine. But the audiable diffrence between the 3 500/1 amps and the 1 1000/1 would be about 1db. However the triamp system would be able to hit lower frequencies. The vitailty of your woofers would not really be sacrificed either. I would do the triamp system, if you could afford it.