@Botjer: That's the beauty of mods, you can use them or not, your choice.
Precisely 
But without knowing the side-effects, how would a potential user, be able to make an informed decision about using it or not?
Best case is a Readme.txt file inclusion which states any draw backs that/might exist.
You do know the "side effects". If you pick one then your going to start with either a Gold mine, Fertile Land, Crystal Mine, Lost Library (Tech Research), Ancient Temple (Arcane Research), Old Forest (Materials), Wild Horses, Wild Wargs, Scenic View (Influence) and Refugee Camp (Population/housing). If you asking if it's perfectly balanced and doesn't disrupt the game then you should test his mod and report your feedback.
Modding isn't a perfect science, it's like research and development which requires testing and feedback. Thus, we need people to play the mods and see what is good and what isn't. Besides, all of these options are OPTIONAL, nobody is forcing you to select one and the AI isn't just going to randomly select one.