When BCY published breaking strengths, 450+ was rated at 155#. 99.9999% sure that was static load, not shock load (shooting a bow would be considered shock).
Pretty sure BCY has made some changes with the dye--dark colors don't seem to "bleed" nearly as bad as they used to.
As for a tiny 450+ string, I don't trust it myself. I know a lot of people have had no problems, but I've talked to several that have.
450+ is 70/30 Dyneema and Vectran. Vectran has almost zero stretch/creep, but it's brittle and can't handle the flex. If the blend were to get off in a spool, you could be in trouble.
Chad