Right now I'm using Keen Targhee II Hiking Shoes. The problem I've run into is that while the shoes are nice for doing walking trails (flat even ground), they just didn't seem to cut it when I did a more strenuous hike with lots of rocks, creek beds, water crossings and tree roots. I was thinking of going to a mid-ankle boot so that I could get some extra stability (I have really week ankles), but I'm worried about the back of shoe pressing too much on my Achilles Tendon and the back of my heal. Rather than asking what shoe to buy, maybe it would be more helpful to ask which shoe NOT to buy. Are there any that you have had issues with not fitting right in the ankle/heal?