In reply to Southern Man: I use Walshes as fell racing shoes, and have always found Inov8s feel fairly wide on my (rather narrow) feet.
I'm trying to understand the terrain you're using them on. Is it very deep (e.g. frequently above the ankle) or more surface mud on a fairly hard pack? I find my Walshes good on the former (though not quite as good as my Swoops, though they're awful when it gets slightly rocky), but I expect with the latter Walshes may be overkill and may trash your feet if used all the time.
If you fit Inov8s I'd be inclined to look at something like the Roclite or previously mentioned Mudroc that has a slightly more aggressive sole than the Flyroc, but not as far the other way as Walshes.