Nice write-up about the poor state of Italian layout. I couldn't have said it with better words.

I totally endorse your proposal NI-2, which makes sense for programmers without too much disturbance for other people. Non-programmers, if can't be convinced to learn to press AltGr to get the accented letters, could even continue adding ' and ` after the vowels, as many anyway do still today.

Two remarks, though, to your NI-2 proposal. First of all, I think you messed up the top row, namely the two keys right of "0". The left one should contain minus/underscore, while the right one should contain equal/plus.

The second remark is a personal preference for î and ï. There are good reasons to to want a clear separation between symbols and letters. Lower case, for example, is implicit and need not be printed on the key cap. Then letters should obey CapsLock, while it doesn't make sense for other symbols. That said, î and ï should belong to the letters' block and feel out of place on the 6 and 7 keys. I suggest mapping these letters to J and K (for proximity with I) and making them obey Shift and CapsLock to obtain î, Î, ï and Ï like all the other letters.

I have one one final doubt: AltGr+E is already "taken" by the Euro sign in some (all?) keyboards. I think you can use AltGr+5 as well, but a deeper investigation is needed.