Ok,
I've seen a few people talking about switching their high lvl rogues and rangers from armor to robes.
I've got a lv 7 Ranger with 23 dex (started with 17, and have a +2 item). I noticed my Mithral BP is already limiting my dex bonus to AC, and in another level, even a Mithral Chain Shirt will be hampering my dex.
On the other hand, it is only limiting dex to AC; my saves/attack rolls/skill checks will be uneffected. And the additional AC from the armor itself seems to outweigh any benefits from dropping the armor. Also, maybe it's just because I'm not a wiz/sorc, but most of the robes I've seen haven't been very good. Something like: Fire Resist 3 and +20 SP is about the best I've seen.
I guess what I'm asking is: at what point do robes really start to overtake mithral BP/Chain Shirt in viability for a high dex rangers & rogues?