Just finished off one of these tyres, so here are my thoughts on the tyre.
The Z6 is Metzeler's sport-touring tyre. It is still available, but they have recently released the Z6 Interact which seems to be an updated version of the tyre.
In terms of performance, I have no complaints with the tyre. I have used it mainly for fast road riding and have had no issues at all. In the dry, it has always provided me with enough grip. I've had no problem keeping up with others using much softer rubber, such as Michelin 2ct's and BT016's.
As for wet weather performance, well I keep it very steady in the wet so can't claim to have pushed to too hard, but again I've had no problem from the Z6.
Obviously Metzeler do not make these tyres to fit the 16" front wheel of older Blades, so I have not tried these as a pair. However I have had both a BT010 and Pirelli Diablo front on with this Z6 and I have found it to work fine with both.
The only disappointing thing has been the mileage thay I got from the tyre. I got exactly 4500 miles from it (to the mile!). I was expecting more than this form a sport-touring tyre. Used in a similar manner, my mate got 2500 from his last 2ct as a benchmark, so the Z6 did much better than that... but nevertheless I would have liked more out of it.
I have replaced it with a Pirelli Diablo Strada, which has a similar profile and tread pattern to the Z6 but hopefully will last a bit longer
So overall, a good tyre, just a bit disappointed with the mileage. I will try other tyres out before going back to these.