Making Prepared Casters Spontaneous

[Cratai]

What would be the effect of allowing players to make prepared casters spontaneous? Would it mess up balance entirely? For which classes would it have the greatest effect? And can someone point me in the direction of the 3.5 book that had something on this?

Thanks muchly

[SilvercatMoonpaw]

Cratai wrote:

And can someone point me in the direction of the 3.5 book that had something on this?

I can do you one better:

http://www.d20srd.org/srd/variant/classes/spontaneousDivineCasters.htm