Actually in theory it is a nerf to all dmg abilities. Except in the case where an ability is indented to clearly deal dmg directly to HP for example crypt Lord's ult will use true dmg to take directly from a users health.
You can see this either as a buff to races that get more armor or as a nerf to all regular dmg abilities as this will overall increase the survivability of everyone against abilities in general.
In testing I have found that the game does physically limit armor to 127. I will thus need to make a plugin that explicitly tracks user armor values and adjusts them as needed. All programs that change armor will need to be updated to use it but the conversion should only require a recompile thanks to the use of my stock functions.