I shred large quantities of woody material every year (up to 100 cu. ft). I would never use it fresh as mulch, but always mix it with the previous autumn`s leaves, which means it then has between 2 and 3 years composting. I then use it as mulch for anything that needs mulching, with excellent results. Its one great drawback is that plants which normally make small clumps make plantations, couch grass spreads like wildfire, and every windborn seed which lands on it germinates and grows like mad.
However, Ceres is right, a lot of the timber cut by tree surgeons is already diseased in one way or another (particularly in tree preservation areas) which is the main reason for their employment, and I wouldn`t want the risk.
I suspect that a qualified tree surgeon would recognise Armillaria anyway, would probably have an outlet already available, and not offer the chippings, but for so many of the `Tree Surgeons`who offer their services read `Traveller with Ladder, Chainsaw and hired Shredder`
