Paradigm or JL subwoofer

Good call to stick with what you have. You will be happy with that. 
Each time my JL E112s broke they changed out all of the electronics. This last time they change everything (including the driver) but the box. I basically had 4 subs fail. My current two have been going strong for about two months…. Fingers crossed. 

This is for Home Theater? 

Paradigm SW1000's, JL Audio F 112's?  One "sounded far better," where? Your room or mine? That Paradigm margin is quite attractive, eh? 

After first hand experience with the F series and Paradigm, I wouldn't choose either. Not for their lack of quality performance but for their stunningly limited low frequency processing design.

I'd suggest auditioning a dealers JLAudio F series at home with your current sub. They both have XLR in/out. Check first but I believe you could use either's processing to run both. and make an informed processing decision yourself.
Their subwoofers, they don't need to match. 

In the end JL's CR-1 crossover may be your best investment.

@james633 Does JL use silicone calking over their boards?   

Not sure about the silicone caulking. The local shop did all my repairs. 

Long and short, 2 is better then 1.

I'd double up on what you have already, which is what I also did when I was entertaining a costly sub upgrade.

I'm happy with my double KEF set up, as opposed to buying two new SVS sub's.

Yes it does not make sense at all to take a big loss on my Paradigm sub. I have no doubt I could have bought something better for less money but at the time I thought it was best to match the sub to my speakers. I will buy a second one