Well, for my side, about the rules, given than RQ6/Mythras has been available for a while, I can't see many reason to use MRQ I & II or refer to it.
About Glorantha content, I have no issue taking ideas in the best books, S&P issues or Living Glorantha scenarios, as I do with every other fan material.
By the way, about Living Glorantha scenarios, as they are still available via web.archive, I'm wondering if we are allowed to link to them, or if there is a licence / ownership issue?