Dear artag, first thank you for the pics. But I think we need to get deeper into this.
In your first link, Igor does mention that LZMA2 is better for already compressed data: "Also LZMA2 is better than LZMA, if you compress already compressed data."
However it does not imply skipping of the compressed chunks and your results actually prove it. It may imply better operation with said data.
Specifically, your data show that
FA LZMA is in fact almost twice as quick as 7z LZMA2 on same thread counts! I assume here that since on FA you used only LZMA and I dont see any 4x4 there, that FA only used 2 threads. That would compare to second pic with 7z LZMA -mmt=2 output,
not the last one that take advantage of more cores.
Also, while newer LZMA2 does give better ratio with compressed data - implying more efficient work, it still does not have anything to do with "skipping". If you want to see what true "skipping" is, compress said file with default FA -m5 parameter. Fa -m5 skip for real, invoking raw disk copy, you would not see 6mb/s like in your pic but almost full disk speed(and not because more cores being used). What you are showing have nothing to do with real data skipping, everything to do with more efficient operation and author also did not said anything like that. You misread his comment.
I already have data I collected yesterday for my next big post in this thread, you will see the difference. Soon...
PS(Btw RZ is this:
https://encode.ru/threads/2829-RAZOR...based-archiver)