@Esfafadro
Tob has some effect on soa areas, the drow in the underdark can see invisible, you can delete spells from spellbook, the xp cap is set to 8m, and there's a certain tob area where you can go before finishing soa.
the addon package that affects a store in soa is the bonus merchants addon that can be downloaded from the gamebanshee site
http://www.gamebanshee.com/downloads/bonusmerchants.zip
If you want a challenge I would also recommend the the improved AI addons.