I have used the Cashel Long Nose/with Ears style on all of my horses for many years and have never had any problems with them. I think they are great quality fly masks, all of mine have been very durable and lasted for many seasons. They seem to be comfortable for my horses to wear for all day turnout, they have never had any rubs or other issues from wearing them. They keep my chestnut, who has a white stripe and pink on his nose, from getting a sunburn. I prefer to use a fly mask with ears to keep the blackflies and gnats and all the small biting flies out of my horses ears.
Only very occasionally have they ever come off during turnout, I suspect after a very good roll in a very muddy area, as that is where I found them covered in mud where they have obviously rolled in. I never fasten the velcro tightly, if I had of fastened the velcro a bit tighter they may not have come off, however, they usually stay on for most rolling.