Re: dark montreal??
Yours must be a dry fly version with that stiff hackle collar. There are a lot of versions out there, the ones I'm familiar with are wet flies with a claret wine red body and a sparse soft, webby collar of hen hackle and hen fibers for the tail rather than the good quality dry fly rooster hackle and stiff tail of dry fly hackle on yours.
it should be good in fast water as a general attractor- searching pattern or for imitating dark may flies that might be hatching, and a great prospecting fly for small mountain streams.