I've always thought that there would be a better way to get around things than Lower Resistance. For example, suppose there were a 5th level spell called Increase Effectiveness (or something even cheesier) that increased your effective caster level, but was school-dependent. So, you cast it, and select evocation, and, for some duration, all the caster level checks you make against SR, when casting evocation spells, get some modifier (+4, in all likelihood). You can cast the spell multiple times on yourself or others, if the same target gets multiple castings, each casting is for a different school of magic.
Then, of course, you put this in a Rod or Staff, and use it to cast SR-buster spells all day.
Dave