First of all, I should say that AI money scripts in Med II are a necessity.
I do believe there is a downside however and the downside comes when the human starts conquering AI settlements, which the human will invariably do. The AI, will all its extra money, will tech up its settlements quite well and far faster than the human with comparatively paltry resources. Once the conqering starts, the human essentially gets access to all the top tier troops without actually having to build much in the way of improvements.
So money scripts make the game difficulty at the start, but they struggle to maintain the difficulty once the human starts conquering. The person that can find a way round this will have created the ultimate mod.
Dave, is there a way?