I'm just wondering how you all handle the Channeling/metal armour conundrum.
In the original RM2 Spell Law, Channeling users in metal armour cannot cast spells (or have high ESF penalties when they do).
In RMC I, however, players were given the option of allowing Channeling users to wear plate armour, since it seemed odd to have classes like Clerics and paladins in leather.
Personally, Essence spells seem to be the best offensive spells in the game. While Channeling and Mentalism users get many very powerful spells, they pale in comparison to essence users (especially magicians) when it comes to elemental attack spells. So I always suspected that was the reason that ICE relented in RCI and eased up the restrictions on Channeling users.
One thing really needs to be set straight here.
At the old ICE, those in charge of publishing the Companions did so with mindset that anything could be included and if gamers used it, then it was their own fault if it was broken. They never even tried to consider play balance as an issue in regards to the options that were presented in book. Grammer and spelling was the only editing that was ever really done.
It is also recognized that there is an element of power creep that occurs over all of the Companions, with new professions and spell lists and options getting progressively more and more powerful. Of course, this means that the first Companion or two were less inclined to have bigger elements of power creep, but those elements are still there.
This option from RoCoI is not ICE "relenting", it was the author adding in a new option for something that he wanted -- much like you are considering for your game.
My suggestion -- do not make it a blanket freedom to wear metal armor -- not all channelers will have that capability, make it like some sort of talent that is required to be purchased by members of specific religions, and then only by those religions for which it would make sense.