Just in case anyone stumbles across this by raising the same question, I ended up with a pair of Adidas kanadi 4's.
Used for the first time in anger this weekend at Joydens Wood 10k.
Mud, sand, shingle and plenty of tree roots and hills. They performed very well.
Oh and in answer to the question above, I'm not sure which models of innov8 and salmon I tried, the ones they stock in snow and rock. I have a very wide forefoot which was the problem, so it was me not the shoes.
The Adidas are still a little narrower than ideal but this is basically something I have to live with, they seem to have a bit more "give" than the others so suited my wide foot a little better.
Edited: 17/09/2012 at 09:05