I'm not against making changes to oberon, my main concern is just that he doesn't end up op, gets some kind of knee jerk, hey this isn't ok, change and ends up in a worse spot. converting the armor to damage reduction probably wouldn't do this in all honesty and I don't think DE would chose to nerf this or him as a result. I choose to believe DE won't nerf something unless it's excessively out of line, but sometimes they do make changes and we complain about them. I personally have loved him ever since the rework they did around his prime release, I played him before but I changed things a lot after that.
You can still armor strip the eximus even if you can't cc them which is generally what i'm trying to do with reckoning when i use it. you can also do this to some bosses and enemies you can't cc, like sargas ruk, or zariman angels.
I also feel like I can handle everything the game is going to throw at me, i've been able to do steel path circulus just fine when voruna came out, which starts at enemy level 180, but i know i put a lot more investment into my oberon than the vast majority of players will.