In general, people who use McHale's packs like them. But the same can be said for most high-end packs on the market. Certainly, for some people there may be benefits for getting a pack made to very precise fit specifications. But otherwise, the simple fact is packs must obey the laws of physics and anatomy. Backpacks are an inherently inefficient means of hauling gear, which is why people in most countries carry large loads on their head.
Backpacks compress the torso, restricting breathing.
And they constrict the hips, limiting motion. So I'm suspicious of anyone, including McHale, who claims his pack can comfortably carry loads of 75 pounds and more. Life just ain't that way. It's a load-carrying champ, and comes in so many size variations I find it hard to believe someone couldn't get one to fit. Get the McHale if the cachet of a custom pack really means something to you.