I found the Metz OK with no real complaints except for wear - until I switched to Avon. There was a big improvement in dry handling and the ride was smoother. I've pushed the bike about as hard as you can on winding roads and it handles like a dream. Have heard others say they're quieter too but there's no way I can hear that over my exhaust.
In the wet it looses traction fairly easily under hard acceleration in all gears, but so did the Metz. Seems sure footed enough round the bends, though, but I don't push too hard in the wet.
Probably had a more noticeable thandling difference when I put Avon on the front, IMO.
For me, Avon offers better handling, smoother ride and hopefully about 50-100% better mileage (and was $10 cheaper!!). I think they look better too. I've also commented before that it seems to sit flatter and therefore wider than the Metz, which would mean slightly wider contact.