Right now on LIVE I feel Darius is an extremely good hyper tank at the moment thanks to the % missing health he now has (I like this new play style of playing Darius as a scaling hyper tank rather than a lane bully, the heal and waveclear helps him get through the lane), so to keep him more balanced I would keep the overall damage lower so revert the PBE buff and keep the base damage at 20/40/60/80/100. Because playing him as this invincible late game tank that pulls things in to him in the middle of the enemy team I feel gives him a better and more viable role within the game, and when players discover the strength behind the % missing health heal his Q now has I think he will be played a lot more and in competitive play as well. So max rank and CDR with health and resistances late game makes Darius incredibly strong and more base damage (and more damage in general) will just make him too strong.
Short end of this; wait to see player exploration of the Darius changes because right now he has an incredibly strong late game thanks to the heal with Q spam especially with cooldown reduction and sitting in the middle of the enemy team absorbing a poop ton of damage.
BUT If you want to buff anything for Darius consider doing it for his W since the spell right now is the first point is really good but the other ranks are not that great for ranking up the spell, only decent since obviously 1 less second base cooldown is good especially for the 90% slow. So perhaps a slightly bigger per rank cooldown [for example 1.25 seconds drop from 1 second so max rank is 4 seconds instead of 5 seconds] or even a slow duration increase per rank (at most would be 0.25 second or 0.2 second; this be 2 seconds or 1.8 seconds 90% slow at rank 5);
but in the meantime I would stay away from granting damage buffs to Darius since they can make it a little too strong especially since his bleed I am think may be very underestimate when it does most of Darius' damage but is not upfront so it goes unnoticed