I ran them for 10k (mostly motorway) miles on my 330d. Rears were down to *ahem* beyond the legal limit. That's soft by anyone's standards - driving hard they wouldn't have lasted anywhere near that.
I've still got the 452's on the front, but gone for the Kumho KU39 on the rear, and so far so good. Similar price, to within a few quid, equally quiet, grippy and comfortable. Wear after 4 months seems on a par with the Falkens though, so I think next time I'll go for a premium tyre and see if they last a little longer.
Just how many Yorkshire sheep can you fit inside one exhaust?