I'll be running a half next Sunday and attempting a good time. I have two pairs of shoes, same model. One pair has about 230 miles on them. The other pair is brand new. Last week I ran in them twice, 8.5 miles each at a decent pace, with no issues, but obviously they're not formed to my feet the way the other pair is. But the older pair, even though they've definitely got many more miles in them, I wonder if they're a bit too broken down for best performance.

These are Nike Triax Structure 16's, I like the cushioning they have but don't necessarily need the "structure" part - they're just the shoes that fit.