Listen very carefully to what I'm about to say. These have a huge damage reduction on their head--about 50%. The application for this is twofold: first, never pump tranqs into their head, it will take about 50% more. When taming, get above and shoot for the back. Second, because the player is protected by their head while riding, they are actually quite good for mid level raiding. You can hide behind it while riding on top, either shooting rockets or dropping c4 (it's like a built in riot shield). Furthermore, they can tank auto turrets as well if not better than turtles simply because auto turrets always hit their damage reduction area! In short, if you are using turtles, you might want to consider a high level trike as an alternative.
I can not stress enough to my friends how useful the trike is. Early game it makes a great pack animal. Late game in groups of three or four it can be used as a decent battle mount. Taming a trike early on can be a great way to start a large base and keep you well fed with berries.