In my country (Slovenia) they traditionally used bracken for bedding
(Slovenian wiki here). Which was very likely brought back to the fields for fertility next year, so I don't think the allelopathic compounds are an issue in this case.
Some even say bracken has a detterent effect on slugs and mulching with bracken keeps slugs away.
So personally I think no harm should come from moving around bracken once in a while. Or mulching fruit trees with it. I'm not sure it is appropriate for the garden, but some shred it and use it like that for mulch.
