They still work but get a point where you need to clean them very often, or you get a Weak Battery alert when hitting it. Kat feels the difference in the hit too. Me, not as much, but the alert got to bugging me.
KTM said that they added a 2nd wire or something, and that was an unnecessary addition. My guess is that it's related. I could definitely still use them if I wanted to, but the JACs came out, and the VTs were competing with something they simply couldn't beat (same general size & shape).
Like I said - I LOVE the look, and I've got a nice spot on my museum shelf for them.