I fully clip my horses each spring. I hate it because hair gets everywhere in all of my clothes and is soooo itchy. BUT, it is so worth it when I do it just before shedding season because I really don't have to deal with that.
I really like the look of those different levels of trace clips - good idea depending of the level of exercise for each horse. One of my 4H kids who has a fat pony, could really use one, as he gets quite sweaty in his hot coat the one time each week that he does 4H rides. My horses don't really sweat during winter riding (lighter coats, and ridden regularly), so I don't have to mess with it until spring.
I will agree that sharp clipper blades are a must...it really starts hacking at the coat when they get dull. Doing a whole body, they dull fairly quickly. I have to do my large blades every 1-2 horses.
Great find on that site appy...I like the visuals with descriptions.