Wot Pieface said. The original Mudclaws tore my heels to shreds, no matter what I tried (moulding the heel cup after warming it up over a steaming kettle etc).
It was a real shame as I have never used fell shoes that were so grippy before. Prior to them I had used Walshes and Adidas Swoops. Both pretty good, but not sure if you can buy Swoops any more? I swapped back to Swoops for a while, but while they grip fairly well on wet grass and dry trails, they are awful on wet rock, just lethal.
There seems to be a smaller and smaller market for fell shoes now. Maybe because Inov-8 are taking over? When looking for a new set, I found some Inov-8s on special offer, and took a punt on the Bare-Grips. They probably aren't for everyone as they are extremely minimalist, but they've been a revelation... all the grip that I remember from the Mudclaw, slipper like comfort and light weight. I can't vouch for other models, but it might be worth trying some on again?
Personally wouldn't wear Salomons for running anything in - heels are too high for me. Mostly personal preference, but when fell running they are asking for turned ankles.