Since mithril body is going to be required to get the Divine Champion enhancement in war soul for the doublestrike, doubleshot & seeker (thus locking you out of the handy stacking DR from adamantine body & capstone), it really needs to be somewhat better for defense... my suggestion is to amend it from a fixed +5 MDB to +5 +1 per 3 character levels - that'd put it up to a basic +15 at level 30, much more in the range of the more mobile medium & less mobile light armours.