Endur: How convienent:
Well, yes, the Dwarf still has to wear plate armor. The extra movement from light armor isn't worth it.
DD has to have a dex 13+ (pre-req dodge feat). Assuming point buy build, that means a Dex 14. At 9th level, maybe you have gloves of dex +2 for dex of 16.
If you are wearing a chain shirt, your ac is 4 + 3 dex = +7 + magical bonus.
If you are wearing dwarven plate, your ac is 8 + 3 dex = 11 + magical bonus.
So, the optimal Dwarven Defender wears Dwarven Plate (mithril). Second best armor for a Dwarven Defender would be Adamtine plate.
I find it facinating that while it's imporant for you to maintain parity in the point buy for stat, it's not important for you to maintain in equiptment.
A Chain shirt is 100 GP, while Mithiril Full plate is over 10,000. hmmm - not a very equivalent.
You also missed a step in the Armor: Mithiril Breast Plate (Add's 4,000 GP). So here is my new, $ to $ comparison.
+1 Mith breastplate (5,400) and Gloves of DEX +2 (4,000) = 9, 400 GP
AC: 6 (Armor), and 3 (Dex) = 9
Mith Full plate (10,500), and NO gloves = 10.500 gp
AC: 8 (Armor) and 2 (Dex) = 10
Now that's a little closer isn't it? And with my extra 1,100 GP, I'm picking up a cloak of resistance to my reflex save is now 2 higher than yours!
Finally, let's take things to the n'th degree. Max dex bonus for Mith full plate is +3, and it's +5 for a breastplate, so total protective difference between the two when fully optimized is 1.
Yes, DD's are supposed to be Dwarven Sentries, so they get spot, listen, and sense motive
What, aren't fighters, or wariors sentieries too? Why don't they get spot?
And what does Cleave have to do with movement? For that matter, you seem inclined ALWAYS to be using the DD defensive stance. If it's not appropriate, Don't use it! It not like rage, where you should use it when angry.
And for your Dragon example? A young adult Green dragon (CR 10) has a Attack bonus of 22. Horrifying, I admit. But your AC should've been 30 or higher! (+8 Armor +3 DEX, +3 Shield [+1], +1 ring of protection, +4 defensive stance +1 Dodge). Did you fight defensively? Did you have any cover? It is assinine to try and toe to toe with a dragon at any level, and expect to come out untouched. Still he had a 40% chance of missing you with his primary attack, and 65% chance of missing you with the supplementary attacks! That's pretty good in my book.
I could tell you about the time I went from 100 hp to 0 hp in one round from an improved invisible, sneak attacking Wizard/Rouge, but that ONE combat does not prove a thing.
but it does serve to illustrate my original point. A L2 Dwarven Defender would NOT have been snuck attack by that Wiz/Rouge. Why? Uncanny dodge.