What is your working definition of gimped? The easiest gimp for casters i ever DMd was: the casters max spells per day was reduced by two in every level. In that scenario you are just as strong as normal at low levels, only a bit weaker at mid levels, and fairly well decreased at upper levels, but you still get access to ALL THE SAME STUFF.
It seems like all you have to do to gimp is take a level or two of something useful but lame. A level of rogue would allow more skills, and a level of cleric would give some self heal, and then you would be gimped?
or alternately (what's gimped?) take Mystic Theurge but without any cheesy entry, and you would have lots of spells, but lower caster level and spell access, which is quite a gimp (imho).
Oh wait. I see who posted. I am sure you know everything i would say, except perhaps the first point.