My very itchy pony got into an area in my field where I have a very sturdy shed and nearly demolished it scratching his tail.
The rug survived with just a couple of small holes, luckily pony didn't do himself much damage either.
Only thing I don't like about them is the is the reinforced bits with the logo on along the neck, on two of mine the stitching wore out in places, I worried he could get a back leg caught up scratching his neck, so cut them off.
I've got both mine in the Weatherbeeta Kool Koat Airflow combo ones. The upper part is a slighter tougher material so stops the coat getting bleached in all the sun we don't have and the lower half is a mesh to ensure there is still a throughflow of air and its stops the flies.
They seem tough - one of them in its second season and is still in perfect condition and thats on the horse who is a complete idiot in the field. I particularly like them as they stop the horseflies getting through which are horrific where mine are kept. Both mine live out 24/7.
Not a bad price too. I've had bad fly rug experiences with the Amigo Mio (fell apart), Mart Todd (rubbed them both around the shoulders) and the Shires (just plain rubbish!).
I love the weatherbeeta ones. Mine have lasted really well, even with my mare who loves to rub and my gelding who delights in tugging at it. However, I found it was not dense enough for my TB who still got bitten through it! I had to buy him an equitheme sweet itch rug. It's a pain to put on but it makes his life in the field bearable.
Ours have the Rambo 'fly buster' rugs - they are definitely robust, last for years and get put through a lot when they're all in together (hooligans!)
They're not the softest of rugs though so if your horse is very sensitive it may rub a bit. Lots of people recommend the rambo sweetitch hoody which I haven't tried but it may be softer.