I really like the Korth, it opens so nicely with the IKBS. I'm not a balisong guy but from having this knife I can definitely see why IKBS makes for a sweet bali. I've been carrying it pretty much every day since I got it and it's getting some good use.
I haven't had the Firetac that long, and while I'd prefer not to put much use on it I have no doubts it would handle anything I threw at it. The TNT isn't really used, just admired for the most part.