Quote Originally Posted by ddude987 View Post
with no early entry shenanigans the trick goes off at level 15. That is pretty late enough that the powerlevel of casting the entire cleric list spontaneously versus being a regular tier 1 caster is extremely minimal.
At high-op the difference is indeed minimal. At low-op it's as simple as take this base class + this PrC (which has trivial requirements aside from the fluff one) and bam, T0. Every situational or tradeoff cleric spell would be at that player's fingertips without even needing a night's rest to prepare - status removal, ability restoration, plot-solving divinations, "silver-bullet" attacks and defenses etc. It's true that a T1 with sufficient op could duplicate this level of spontaneity, but 10/10 RS does this with surpassing ease.

This is not to say that there are no campaigns where this can be challenged, but it's easy to envision that the designer intended there to be a harsher drawback than currently exists.