GY Endurance are fairly new (less than a year), so you won't see you many comments on way or another regarding their performance. All indications are that they're good tires.
Nothing wrong with Gladiator tires. I've got 24 of their tires on 5 different trailers on the road all the time. So far only one blowout (happened to be on my 5er), and the commercial tire shop that sells them to me has said they have a tremendous track record.
FTR, I will be looking into the GY Endurance tires moving forward, especially if they show to be a quality tire.