I think it really boils down to your smallest and largest cassette rings; what is in between is a personal preference as to how much of a jump you can handle. I have found the 8 speed to cover this amply. You need a climbing gear and a spinning gear and the rest is somewhat necessary filler, even in mountainous Colorado. 1x10, 1x11 seem a bit overkilly to me - that's just working your right hand harder than a 13 year old who discovered his dad's nudie mag stash. Not that this ever happened, just sayin'.