Brendan was thinking about limiting magic users on Google+ and I started thinking about my own house rule...
I’ve been using the strict reading of the B/X spellbook rules for a while in my campaign.
What I’m seeing is that magic users worry about the spells they will eventually pick because they know the number of slots is limited. Read magic is important because it grants access to scrolls and without it scrolls have no value since you can’t copy spells from scrolls.
What I’m also seeing—but I don’t know whether that is related—is very few magic users and the few magic users I’ve seen are all low-level henchmen to player characters of a different class with levels 4–6. It seems to me that magic users die quickly when the whole party is low level and that’s why my players have been avoiding them as primary characters. I don’t think this is due to my house rule.
What I’m not seeing a lot of—even though I hoped to see a lot of it—was player characters seeking out high level magic users and elves in order to gain access to new spells. The characters learn new spells from the few magic users and elves they meet during their adventures. Maybe I need to add rumors about particular spells.
For now I’m still happy with how things have turned out even though they didn’t turn out exactly as I had hoped for.
More thoughts about reading B/X D&D in the links from my Ode to Ode to Black Dougal.