Dexterity-based characters shouldn't need high AC bonuses from items, or at least higher ones than the ones on existing sets. For example, +6 is the server maximum for natural (amulet-based) armor bonuses. The best armor is +15. 15 + 8 = 23. The best cloth armor (no dodge bonus restriction) is +6. 34 dexterity plus 12 from potions/items would give a modified dexterity of 46. That's a +18 ability modifier. 18 + 6 = 24. I could be wrong, but I believe dexterity-based players have comparable AC to non-dexterity based characters.
Of course, the argument could be made that dexterity-based characters should have much better AC than guys walking around in metal plates. The monsters were designed with AB necessary to hit an AC of around 90, including buffs. Letting players get substantially more than this would make invulnerable players. Also, anything greater than about 80 makes the player invulnerable to the best other players can do (hence spells/items to strip magical protections from other players).
I still see a lot of players running around with really high AC. That bothers me, because I really want to make the monsters less powerful so that people who don't know how to pump up their AC don't have a big disadvantage. I'm certain spells are still stacking effects. If you cast a strength-based booster, that shouldn't add to any other strength-enhancing spell. Same thing for AC bonuses of the same type.
I'm going to have to go through all the spells myself to find out how people are getting such high AC bonuses from spells and spell effects. Once I have that nailed down, I can start dropping the higher-level monsters to something more reasonable. High monster AB throws off more than just hitting players, btw. For example, a knockdown compares the attack roll versus the player's discipline. With monster attack rolls approaching 100, you won't have a chance against knockdown!