Not Richard, but as someone with ponies who spend a lot of time in muzzles I feel qualified to answer your question.
I thought long and hard about the use of muzzles, particularly with the problems associated with them, eg rubbing, and the fact that turning anything out in a headcollar/muzzle has an element of risk. Eventually I decided that the alternative for me at the time, was either to restrict them to a stable, which meant they were isolated, turn them out together in a very small restricted paddock, or allow them access to a bigger area but wearing muzzles.
I discounted the stable option. I tried the restricted paddock option building a paddock with electric fencing which I could then extend as required, the little wotsits soon worked out all sorts of methods to get over/under it (I never knew a 11.2hh could clear 3'6" until I witnessed it first hand!!). We then built a more permanent structure with wooden posts and thick tape but although we were religous about picking droppings up every day, we saw an increase in eggs in the poo samples.
We are now lucky enough to be at a yard where we can have a compromise situation. The ponies are turned out in the early morning in their paddocks with muzzles, they then come in at lunch time to a wood chippings and sand area in the afternoons and the muzzles come off. They are currently in at night.
Even if I didn't have this set up though, I think I would still prefer them out and running around, wearing a muzzle, to going down with lamintis or being kept in.