1. Maybe. That depends if you already have misfires at idle or not. If you do... time to either tune the fueling properly or get better injectors
Absolutely incorrect. Depending on cam setups, you won't even have misfire free idle leaner than 13 AFR on more exotic setups.
Of course this is extreme, but your assumption that the injectors are bad is just wrong.
FYI my only car with ME7 is a bone stock RS4 and that would probably be fine idling at 15.4, but I don't only tune my own cars.
2. There is really no knock present on my car until hitting heavy at 20psi. At least I never logged any corrections at load below 180ish and at this point the car is running on open loop for a long while already getting much richer mixture than closed loop calls for.
If you've never logged any corrections below 180 load, then your timing map is not set up right. That is all I will say.
3. There wouldn't be since all tables are geared towards gradual adjustment. The system doesn't drop from 15.4 to 11 in one step as you'd think. The values are interpolated so it would do it gradually. But that's a very extreme example which will not be representative of real life tuning situation as no table should ever be set up like that.
Please don't tell me what I think. You don't know what I think. You also don't know that I probably have more experience with tuning and ECU's than you, but this is not relevant to this discussion. I just found your statement rude.
With that out of the way, you missed what I told you. You are tricking the ECU to think that Lambda=1 is actually something else. Yet you are not tricking it to think that for example lambda=0.8 is something else, so you will get less gradual adjustment, and not really what is needed in a number of cases.
You will need to recalibrate loads of other stuff to make it operate correctly or update the code a bit.
This with combination of #2 means trouble. If you want to do stuff right.
That's why the *correct* solution would be to have dynamic USR. I would go as far as saying, the USR should depend on LOAD.
And I will write this eventually when I get there, lacking time right now.