Chameleon class and prestige spell advancement

[Kelb_Panthera]

I honestly don't see a problem with it, from a balance perspective.

By advancing chameleon's casting that way you're not advancing any of its other class-features; mimic class feature, ability boon, and aptitude focus (uses per/day). On top of that, you'll only be advancing one version of its casting since many of the +1 casting PrC's specify either arcane or divine.

If you want to essentially give up 4/5 of chameleon so you can use the remaining slow-progression spellcasting like a champ, go for it.