Well, after breaking my ankle in 3 parts with a super-high-cuff extra-heavy hiking boot about ten years ago, I only walk with trail runners.
A physiotherapist friend explained me that ankle support is actually better for trained walkers with trails, because the ankle gets the full sensitivity and proprioception with lighter shoes, whereas a higher boot that serrate the ankle makes the muscle slower to react to un-balances.
The fact is, it works, at least if you're a bit trained.... and the pleasure to walk with lighter shoes is not to be underestimated (at least if you're not too heavily charged, or course - I keep my rebel, thanks ). I really rediscovered the pleasure of walking (light).
The main con of trail shoes could be when you get your feet wet ; I personally prefer getting wet and drying quickly (best with good socks and a small gaiter), rather that macerating in a waterproof-and-not-that-breathable goretex shoe. Matters of taste and perspiration.