I’m currently using qBittorrent in “mixed mode” (clearnet + i2p), and honestly it’s amazing, even though there’s no current DHT implementation for i2p. Sure, you have to configure your client to automatically add the i2p trackers and everything, but it’s a huge step forward IMO.
I’ve also tested how one could “transfer” clearnet torrents to i2p and it went pretty well, even though you have to modify the original .torrent file to be accepted in some i2p trackers (I used postman tracker to test it, and they only accept torrents which all announce URLs are within i2p).
In general, I’ve found qBittorrent’s implementation pretty stable and suitable for day-to-day use, even though it lacks some features.
Snapper also uses btrfs subvolumes to create snapshots, so if you did create them during your installation process, nothing to worry about.
I don’t remember if there is a way to create them after the installation, neither if it’s a tough process tho. I used to simply reinstall when I messed up with the subvolumes.