Two JL F212s verses two Velodyne 18 plus?

Both, I utilize as home theater and listening room. One of my dilemas presently is finding a place to audition these subs.

If your dealer is close buy and he wants a sale,he should let you do a home audition especially if your dishing out lots of coin.
Been thru that a few times,if they don't I'd go somewhere else.
I'm a 3hr drive to a nearest dealer an hour and a half each way.Don't mind the drive if I can get what I want.

I have a local family owned electronics business that can get velodyne or JL at a decent price, but they don't stock any of them. I would have to travel likely five hours one way to attempt to find a demo. The two places I have dealt with before neither have any of these subs in stock to demo. Thats in both Portland Oregon and Seattle Washington.

That's a bit of a drive(one way)
whichever sub you choose hopefully she's the one as getting two gets pricey.
I went thru six subs and been looking for that live bottom end
sound(my dealer also)15's18's,and some W bins.
when I heard the 1812 in his huge room,I was literally blown away.
Mine is alot smaller and I figured,I could never get this sound in my room.
My dealer said,it doesn't matter the size of room.
We'll he proved it,I get the same sound in my 12X19 as he got in his 16X40X12 room,I couldn't believe it.
He brought it up for a in home audition and I wasn't committed to purchase.I guess he was sure that I'd like it.
The wifey made him dinner and I offered to help on his gas for the drive up.
Anyway I get all the lowend theatre I want,plus the midbass Punch for music,this is bottomend you feel up your backside
and doesn't interfere with what's going on above it.
Totally satisfied musically now,wish you could audition up here.

Clean output capability and damping control would be my top priority, were I in your shoes.

I suspect that either of your options will be great in your modestly large room (on that basis), so you probably can't go wrong, but...

If you don't have Audyssey or equivalent, then I'd add stand-alone Room EQ (at least for the subs), if you choose the JL. SVS sells a bass-only version for the sub signal - under $1K and, judging from my experience with the similar Velo SMS-1, a critical component of good sub performance.

The Velo DD series includes an excellent version of this approach, and I'd choose it over the JL (which includes a more rudimentary version) on that basis, but....if you already have the capability in your Pre-Pro/AVR, I'd probably go JL.

You might want to look at some other options, as well. A pair of the big Rythmik dual driver subs (F25) will be far less expensive and (based on my experience with their smaller subs) probably still provide top notch perforance. SVS also makes a highly regarded product that's a lot less expensive than the big JL or Velos.

Good Luck

Marty