I have a pal who is a trail and fell runner. His pics on his runs look lovely (all of that off the beaten track, running through plantations stuff) and so, as I've got fitter I thought "I'll have a bit of that" and bought some trail shoes in an online sale. Long story short - I'm now injured and it's my own stupid fault.
Trail shoes are generally stiffer and lighter than 'standard' trainers and have less cushioning on the sole. The width of the 'toe box' is critical too (the Salomon's I bought were a bit tight so I tried the frozen water trick) and stupidly, I set out on a 10km try out road run on which they were fine at first but, typically, at the point of no return, they started hurting, my toes took a hammering and an old, long dormant Achilles injury has returned. My learnings in no particular order:
1. They have a great grip and are lightweight.
2. Size and toe box width are both critical to selection. They're designed for the trail and so soles will take a pounding if used for road running. Get 'em a bit longer and wider than you usually would other running shoes.
3. They generally have zero drop, so heel and calf injury prone folk beware.
4. There are huge variances in toe box width between brands (I now have a pair of Altras - they major on this dimension so the their shoes look like boats but fit me very well).
5. Trail shoes are for off road, running shoes for on road. Doh!
6. Always take new shoes for a short trial run first - even if this uses up a precious "run day" window.
7. If it starts to hurt, stop. I was in the middle of nowhere when this happened so did a sort of slow jog/walk to get home but knew I was stoking up trouble with every step).
Will I give it another go? You betcha, but I'll be a lot more humble in my ambition next time. Meanwhile, I'm resting up (Achilles injuries are notorious for the length of time they take to settle) and generally being an ursa caput valde. That's your actual latin!