I used one once. Put it on at tea time. When I came down in the morning I had a 'blind' horse! The hood had covered his eyes! It did keep his coat lovely & flat & smooth & clean & shiny so I just cut bigger eye holes. Don't do showing now.
Mine wear the Dragon Suit over night the night before a show. I tied a piece of string to the bit between the ears the bit between the eyes to stop them twisting and blinding him. It's way too big for GrayMo, I should really get him a smaller one lol
I have the body rugs with no neck or head and think they are brilliant, if you use them after bathing they make the coat so smooth and shiny
I notice that a lot of the show people use ones with big eye holes and short noses so there isnt as much material covering the face as other makes, other people I have noticed have tied the part that goes in between the eyes together with string so there is a much wider margin of error if the hood slips
I have a Harpleys 'Good Hood' for the neck and face if I need it as this has huge cut outs for the eyes due to the design
One word of advice - whatever you buy give it a couple of washes first, I put a new rug on a wet white pony and ended up with a blue pony!
I don't use them on over night in case they slip over the eyes I put a clean fly rug on with a neck with a rug over the top depending on how warm it is, then in the morning I sponge any dirt off spray the coat with sparkle spray and put the lycra neck cover on so they travel in it I have even warmed up with it on, they help keep the coat flat and help keep longs manes flat so they look neater.
I use them after i clip/wash to keep a weeeeee bit of warmth and i definitely use them on my cream colour horses or those i am showing near the end of the season when i won't clip them to show (also applys to the first show of the year cause theres always a long break between it and the next show)
I did come into the stable to find my gelding "stuck" with the eye hole in his mouth and he was basically trapped on a bolt, so he has never had it on again. He was not harmed though.