Yes I am giving an ability to casters, it will give them more flexibility and thus more power to them and the party as a whole. I’ve given most other classes stuff as well - not Paladins. But I don’t really want to go through that, I am just posting about these two changes.
I confess, I was starting to wonder what the point was to this thread after this.
Post changes in vague form, say dont wsnt comments about balance, dismiss a variety if comments about what folks see as issues, then refuse to give context (other equitable changes for other vlasses.)
"I hunted around a bit to see how others have dealt with these issues but couldn’t find much so I’m posting this to see what others have done and what they think."
Then I went back to the OP and saw that even tho knew has to expect the responses you get when posting significant house rules, you actually did not ask for discussion of your rules, just posted the long set of rules and buried the lead... you want to know what other folks did about concentration and attunement.
So, in that vein...
As a GM I do not prefer as heavy handed management of gear by GM fiat as it feels like you describe. Any significant facet of "balance" I can make a PC choice and character trait is to me a good thing.
So, for instance, I removed "healing potions as common" and replaced them with "recovery elixirs" which allow your character to spend HD without a rest. So, your "common" healing is using a character resource that is spent and recovered etc. This took away the twixt-combat sack of bonus HP only limited by the GM allow to purchase altogether and moved it to a known character based limited feature.
Atonement to me is another such feature - it takes a lot of the GM fiat for balance and influence out of treasure choices. The PCs can divide loot and I dont have to script the loot for them. For reasons others described.
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For ne that has worked well.
In a prior 5e game, I shifted atonement to be tier+1, not just flat 3, so that again it was character-based instead of flat 3. That fits my taste better, but it did not make much difference and so in the current games I just went back to 3 - online systems hard code it so less work.
For concentration, my campaigns have been fine with it as is. I have made no changes as it seemed to work within the context of 5e system. I have lots of house rules but this was not one i tinkered with.
It seems to me in play that there are more than a few cases where "is not concentration" and its opposite are obviously hard coded into balance between things so before i make any change, any sweeping change, it would require spell-by-spell power-by-power analysis and frankly, i have not seen a driving or compelling reason in play to warrant that much work.
In our gameplay, the ability to disrupt some powerful spells by tactical choices other than dispel magic has added a lot to combat in good ways. Going back to the days where once cast spells just ran and only your casters could stop them as common... would be seen as a loss, a lowering of fun.
So, nope, not gonna mess with removing that from the game.