Was just in this same situation. Went out and auditioned the JL subs, they KICK!
If you only get one, get the bigger one, if you get 2 get the smaller ones. They will put out way more bass than you think, or even need. However, the bigger sub does have room correction. But during my audition, we were swapping them all around, without and DSP, they integrated really well.
In the end, was talking to a friend who sold me his old sub array, 3x10 600w, it is way more then I'll ever need. Like you my mains go down around 36htz, crossed over my sub at 44htz.