Pseudo Cloggy,
I posted something on the Metzeler Roadtec Z6 tire about two months ago in the technical forum.
I swapped out my stock Dunlop D252's for the Metzelers at 8800 miles. The Metzelers are, in my opinion, a great tire. Very good grip and feedback however, after about 4000 miles on them the rear tire started squaring off (flat in the middle of the tread) and I lost some of the confidence that I had when they were new. The tires still have a lot of tread left so I just had to start riding a little more conservatively once they started wearing.
BTW- I believe Metzeler and Pirelli are the same company from what I've read on the internet. I don't know who bought who or when they merged. I don't know if they run independent tire lines or just change the embossing on what might essentially be the same tire so I'll leave that answer to someone who knows more about tires than me.
At any rate, I like the Metzelers but personally want to re-skin with Pirelli Corsa's next time. A friend of mine runs them on his R6 and thinks they're great. Just my 2 cents (pence) worth.
Cheers!