I have the same experience with the 880. Love the tire but have had it on for about the same miles and the tread is almost gone in the middle.
On the other hand, my tire is not that square. I have had a slow leak in the tire since day one so I've had a problem keeping 40 psi
in it. The pressure gets as low as 20 before I fill it. I think that may have resulted in the tire being less 'square' than would be anticipated based on the amount of tread that is left.
As you know "best wear" usually means 'poor grip'. Unless I can find a tire that's as sticky but wears longer I'll probably stay with the 880 as I feel 'safe' with them.