I assume you're trying to compare with the passive Cap? Because Cap 2400 to me implies it'll be mated with the 2400W SpeakerPower amp w/ included DSP. That's the route I'd go, personally, if I had the money and wanted a ported sub, because it's just a stellar setup. Best ported sub on the market for the last several years, many say. It took the crown from the SVS PB-13Ultra.
MK pretty much covered the bases. Your comparison's not apples-to-apples, but yeah.
The better comparison would be the JTR Captivator S2 vs. the Chase SS-18.2P. The only problem there is that the CHT setup is entirely dependent on how you power & equalize it, whereas the JTR setup has all its muscle built in. If you were to compare those two solutions, the JTR Cap S2 vs. a fully powered CHT SS-18.2P setup, it's no contest - the JTR system is two classes above, and will have way more power on tap to give to much higher quality drivers. But, it should - it's in another price class.
If you want to consider some personal commentary about the ported Captivators, ask in the Captivator thread. I've included a few anecdotal notes below, too.
The guy who bought my passive 2011 JTR Captivator (the one with the huge 3-slug, 68lb motor - very similar to a the old Maelstrom-18 or the current Mach5 UXL-18) said it bests his dual 2012 CHT VS-18.1 at the same power levels. I think the biggest difference is the quality of drivers used, since building a simple sub ain't exactly rocket science. The CHT 18" drivers are, last I saw, a pretty cheap, low xmax, single-slug Eminence driver.
Also, when making a purchase like this, it's a good idea to consider the companies you'll be dealing with. There have been a few fairly large issues in the past with the customer service and demeanor of the owner of Chase Home Theater, and it resulted in quite a few bad experiences chronicled here on AVS (where they couldn't be edited after the fact, like on the owner does on the CHT forums).
On the complete opposite end of the spectrum, Jeff Permanian of JTR is a world-class guy, lauded by pretty much everybody he's come into contact with here and in the pro audio scene. There have never been, to my knowledge, any complaints about his service, ever. Only complaints are his lead times to ship product - but being popular does that to a one man operation.
Last thing, once you get it, it's likely your Captivator will hold its resale value much, much better, as long as you take care of the exterior. Mine sure did.