Why wouldn't it still be a good match? Will the sub be operating at it's full capacity? No. Will it still sound good and have decent output? Sure. I have a W6 on a 500/1 and it sound phenominal with a good ammount of output.
It was always understood (at least by me) that JL did underrate their subs. Yeah a W7 is rated at 1000W but you could go a little more should you want to use a higher power amp. I've had many retailers tell me that. You could also deduct that by looking at their power charts.
Allthough the yellow area (optimum) was what they reccomended, it usually went a ways before reaching red and then black (thus being not reccommended and voiding warranty).
I just never thought they were underated THAT MUCH. It will still sound good and work fine. You just have the capability to "officially" throw more at it and JL will warranty it.