It'll be interesting to see how the formulae's apply when they fix Defense Scaling. If I understood what the dev's were saying, an even con Boss's tohit will now be calc'd as (50 - Defense) * (1 + ToHitBonus). Where the tohitbonus is 15%. (currently 65 tohit against a 0 def target).
So, that'd be ( 50 - 0 ) * ( 1 + 0.15 ) = 65. Whereas say, a 35% defense (easily attainable for some sets), would make that ( 50 - 35 ) * ( 1 + 0.15 ) = 17.25% ToHit (Under the current system, that boss would normally have a 30% tohit, 65-35=30).
Which is rather interesting I think. especially with your DRR theory. Taking a 65% ToHit down to 17.25% is a multiplier of 3.77. The dev's say that 1% Defense = 2% Resist. So, compare that 3.77 multiplier to the multiplier for 70% resist, which is 3.33. I like this upcoming change to defense scaling, while it won't help with One-Shotting, it'll protect more against higher level mobs than resist (excepting one-shots). Anyways, love your post and the formulae you came up with to support your theory.