Ok, I must be interpreting this wrong, because it just doesn't make any sense. Is there really no benefit to casting the Armor spell at higher force, the effect is just based on hits after all? Am I missing a rule?

Hits is limited to force of spell.

Thanks, I knew I had to be missing something obvious, but I'm still new to the magic rules and my GM isn't much better (hell, he's the one that asked me that). There's two things I really don't know all that well yet and those are Technomancers and Mages.

For sustained spells such as Armor, the Force at which they are cast also affects their resistance against Counterspelling attempts. (Counterspell + Magic vs. Force + Magic {+ karma spent for Quickened spells.)