I ditched for the same reason - I run btrfs on my workhorse machine. I'm very happy with nextcloud (though it leaves something to be desired as a developer who wants to contribute). The biggest difference though, is that now I have a product that beats the hell out of any cloud storage provider. 6TB of space (drives I had lying around, basically), integrated with Plex and my Roku, encrypted off-site backups (free azure allotment from my work, but pennies anyway), and better use of my internet connection. If I need more space, I can buy it very very cheap as a one time expense. I never have to go back to Dropbox again. Feels good, man.
My personal laptop and desktop are on btrfs and my work laptop and desktop are still on extra; I haven't noticed any difference between how well it syncs between those sets of machines. In fact, after the initial setup of it on a Digital Ocean VPS (20 GB is enough for my uses), it's been virtually the exact same experience as Dropbox for me; the initial sync on each my my machines too roughly the same amount of time as the Dropbox sync did, and every change since then has been essentially instantaneous to my other devices. As an Arch user, it's actually easier to install than Dropbox (nextcloud-client is in the main repos, whereas Dropbox is only in the AUR), and the Android app has also worked perfectly for me. Assuming you're okay with a bit of upfront cost to get the server set up (I basically just followed the Arch wikis and then used Let's Encrypt for the TLS certificate) and the cost of a VPS, I'd highly recommend it for people who want filesystem sync'ing for non-ext4 on Linux.
