I use style boots for xc, they offer fantastic protection with the solid metail inserts to protect from injury, never slip and made out of really tough fabric so they will last a lifetime!www.styleproducts.co.uk
Personally have experience with the Style boots but not overly keen. In sandy conditions, the dirt gets trapped in the binding and then can rub the leg. But as you say good tendon guards, just don't like the risk of rubbing.