I've worn trail runners for all 55 Colorado 14ers. Have gotten my ankles dinged up a few times but I like the light weight vs a boot. Trail all the way up Grays/Torreys and also pretty much the same for Quandary but as SaltDog mentions there is some talus near the top but I had no trouble with running shoes.
Oh, yeah, forgot to add: once off the summit you'll be glad about the trailrunners again!
