As I tried it myself:
- Boot time was almost half.
- I could have with TimeShift earlier snapshots in grub I can boot from.
- The downside I had that Baloo went crazy (more details in this thread Baloo is The Responsible of Unresponsivenes)
So, unfortunately, because of each file appears multiple times and Baloo keeps reindexing… I reinstalled Ext4.
Though BTRFS seems really promising, but not for me at the moment.