Earlier quoted context omitted.
You may call my opinion BS but it is harder due to the fact that additional letters take space off the symbols. Examples (assuming you use AltGr) Symbol; English; Russian , ; , ; Shift + . [ ; [ ; AltGr + х { ; Shift + [ ; AltGr + Shift + х See pattern? Though I agree with you - it's not a dealbreaker.
Ok, two modifiers are proably more annoying. Is the Alt-Gr plane not big enough? I have serveral Symbols there that i never ever need, like ðæł¶ŧ←↓→øħħ̣ĸ . Are there essential Cyrillic characters?
I could set up a lot of symbols though altgt but they won't mostly much English layout. But I don't need to because languages I program in are English based.
If I knew German, I would use exclusively German layout as apparently you do. But I need actually 4: En, Eo(that not much but still), Uk, Ru - those two every day. So I contracted it to 2: Latin/Cyrillic. :)