I have both trail runners and boots. I use them for different trips. The boots are not for support, they are for when I expect wetter conditions and for the winter for more insulation. In my experience the concept of support is overrated and actually can be a negative. My ankles are plenty strong to support my weight and can handle uneven ground. In fact, on uneven ground is when I choose my trail runners. Having boots which do not allow ones ankle to flex forces tension at my knee. Over a long hike on uneven ground my knee will start to hurt while wearing boots due to forcing the stress away from the ankle. There is much more mobility in my ankle than my knee, it is designed to handle changing ground conditions. Unless one has a medical reason for needed to brace their ankle, boots are unnecessary for this purpose, IMO. Like I said I still use my boots, but not because of ankle support.