Checksums seems to be the same. Around 35% in average, depends on files stored in Bin/ISO image.

No way, I dont trust cloud storage at all. Offline storage is mine forever, cloud storage is yours temporary with an invisible countdown timer. And btw Ive read a few months ago that Archive org has an open lawsuit regarding digital rights storage, or something like that…

Thanks for your answer, yeah I m worried about that “Last Modified Original Date” thing. For now I will keep only 7z compression for storage, just to be sure. Maybe I will use the ECM method in the near future when I will be able to duplicate my files on a second backup drive(s).