They love it!
Aiming to give my active dog an energy boost for his beginners agility, and to get my lazy dog a little trimmer, I decided to give this 80/20 a try. After bracing myself for the cost, I switched them from standard dry food and a bit of meat, to this and a bit of meat.
Well both dogs love it, lazy dog has sleeked down a trifle without increased scrounging, and active dog is full of beans, though energy level hard to quantify.
It seems to satisfy them with a smaller volume and weight than grain based food, so, while pricy,means it works out not quite as expensive as I thought.