I replaced the D404s with MT66 and for a while I thought I'd made the wrong choice, as they took longer to scrub in properly than any bike tyre I've ever had. Hopefully that means they'll last a long time, I don't know, but they're showing little or no wear yet (after maybe 3000 miles).
They're working very well now, much better than the Dunlops, and I'm happy with them. But next time, screw longevity, I'm just going to buy the tyre that grips best and soonest. The problem with the Dunlops is they don't even make up for short lifespan by having great grip.