Hmm. I've never had a problem with Kenetrek's insoles at all. I've destroyed two pair, and have never had sore feet. Their insoles are built in. I've added $60 top of the line liners to see how they worked, and ended up with rub blisters on the back of my heels. Personally, I'd never screw with my Kenetreks again. Boy, was I pissed. I can't speak for the Lowa's though, as I've never tried a liner in them. I also have a friend that added nice insoles to his Kenetreks when they were new. Four months of breaking them in later, he was still getting heel blisters when hiking up hill. I asked if he had ever tried taking the insoles out. He said no. He took them out, and has never had a blister since. Just like different boots fit different peoples feet, the same is true for liners in my opinion.