I just have to add my two cents to this discussion.
Ride what you want to or better yet, ride what your horse wants to. Some horses are great 100 horses (i.e., my horse Windmere) Some horses don't have the patience for 100's (i.e., my current horse "Valium") He would go crazy on a 100! He likes 25's! His philosophy. Are we done yet???
I think endurance riding is growing as sport and needs to expand it repertoire. To give out awards to only 100 horses would eliminate those wonderful 50 horses that live for the challenge.
Just love the skin you are in! ( or better yet, the horse you are on! )