In addition to taking a look at crit talents, perhaps it is time that Illumination got normalized. Currently its effect varies wildly with the spell. With Flash of Light, a crit will restore 123 mana/sec. With Holy Light, a crit will restore 306 mana/sec.
Essentially, Illumination is almost three times as good with Holy Light than it is with Flash of Light.
I think Blizzard does not have an issue with paladins having really high crit rates on Flash of Light. Witness Sacred Shield, which gives the paladin an occasional 50% bonus to FoL crit rates. However, when Holy Light gets really high crit rates, things go crazy.
What I would suggest is weighting Illumination in favor of Flash of Light. Something like a FoL or Holy Shock crit returns 75% of the cost (153 mana/sec), but a HL crit only returns 30% of the cost (153 mana/sec).
(Numbers can be adjusted for balance. This is just a demonstration.)
Of course, Sanctified Illumination would be really bad, so that talent will have to be replaced. But the crit talents need to be looked at anyways.