I don't agree that concentration was faithfully implemented.
Damage is applied by increment rather than total, so I regularly have to do 2-3 con saves on a single attack. You lose concentration on being prone, on any hard cc (paralysis for example) and also, constitution modifiers are not always applied to the save (this may be a bug, but i've seen it a few times).
I see I haven't payed sufficient attention to the combat log in my 50 hours of play. Rolling for each damage type/instance is indeed pretty bad. I realise it's necessary to account for damage reduction and such, but I find it hard to believe they can't then summarize the damage dealt and roll against that once.
