When to give up on a boot?

[jhoff04]

I also have heel slip problems with several boots, it just seems inevitable. I have a pair of Kennetrek NI Mountain Extremes. I love the boots, they're formed well, great support, comfortable, and have well over a hundred miles on them but still can't figure out how to completely eliminate the heel slip. I just run strips of KT Blister prevention tape on my heel. I keep a roll of it in my pack and it's served me well.