I have 10k miles on my Siracs, almost all motorway though. You must have a very heavy right hand if you've chewed through them in only 1500 miles.

My replacement will be Bridestone BT45 for my Tenere. I'm not certain they'll give me any better life but as they are a normal road tyre and not knobbly I'm hoping for a smoother, quieter ride on them and less cupping on the front (which makes the bike quite uncomfortable in a crosswind)