ps, i can vouch for the Saucony Ride 7s, I have done close to 500 miles in them now and they look like new. The soles on them are really tough! They are a light shoe as well (in comparison to other well cushioned shoes)
Mine normally last around 6 months but depends how many pairs I'm rotating at the time. I usually go over the recommended 500 miles unless they look buggered or I'm feeling niggles in them. I wouldnt normally go much above 600-650 miles though.