No, I would put Xc or brushing boots on, open fronted tendon boots will offer very little protection if the horse clips a fence, hence why they are open, so if the horse rubs a pole they feel it.
I wouldnt use open fronted tendon boots for anything. If a horse needed boots due to brushing I would use brushing boots, but other than that, im not convinced that kind of boot has a use, as there is currently research going into them as to whether they would actually prevent a tendon injury, or make the tendon more liable to injury due to the extra heat retention...
No ,would use xc boots. I use open fronted tendon boots for SJ in case my horse strikes into himself ,with a hindleg ,into the tendon. I also use over reach boots.