Following the death of my archer in the World's Largest Dungeon, I created a spiked chain monkey (half-orc Bbr1/Clr3/Ftr2 with Cbt Expertise, Imp Disarm/Trip and the PHBII cleric option to spontaneously cast domain spells (Strength) so that I can get Enlarge Person and Bull's Strength on demand - aiming for Exotic Weapon Master).
His purpose was specifically to support the dwarf and elf fighters rather than to deal raw damage. So far, through a level of playing (just picked up Ftr3) he would hardly be labeled as overpowered. He is useful for the AOOs, but plenty of creatures can't be disarmed or it isn't worth the risk in trying to trip them (large or larger, stability bonuses, massive strength etc).
So not bannable in our experience (I'm the first player in either of our two 7-player groups to have taken a spiked chain since 3.0 was introduced).