I use Dropbox to sync the file through multiple computers including my Android phone. I don't fully trust Dropbox for sensible stuff, but since the passwords file is encrypted by KeePass, I consider that if Dropbox ever gets compromised, they won't be able to access the contents of the file right away without a lot of work.
The passwords file uses a long password, one of the few passwords I still have to remember, plus I use a keyfile for encrypting the file. That file is not allowed to be uploaded to the cloud. I have a copy of the keyfile in my laptop, another one on my Android phone, and another one on a Veracrypt partition in my thumb drive.
It is not a perfect setup, because I still have a few issues that I haven't considered, such as how should I proceed if my phone or laptop bag ever get lost or stolen; but it's convenient for me at this moment.
command-line, encrypts passwords with gpg, synchronises using git and by default only copies the password to the clipboard and automatically wipes the clipboard after a minute
For backup, I use duplicity to encrypt my .password-store and all other private files. I have it spit the output to my dropbox folder so it syncs automatically.
This keeps what sites I have passwords for hidden from the outside world.
I've looked a little into keeping the entire .password-store folder encrypted locally until I try to use it, but I guess I'm not paranoid enough for the hassle.
$ ./pgen.py foobar.com foobar.net foobar.org
foobar.com: Aa0$d8~04h4W}Oj-MWA5 Aa0$eaxxF4XzaDaOnx5o
foobar.net: Aa0$q;7uc=@(4nSS5PIF Aa0$pG5+6ekXTONYJXrE
foobar.org: Aa0$%YY$Dle*&(egUuL1 Aa0$y4AhSpO64xF+Aa/l
I use Mac for work and Windows/Ubuntu at home. Enpass is the only solution I found that works for all three OS perfectly.
It was actually interesting to work on a new file format. The version 1 was not formally versioned. I realised that for the version 2, I would need to add a version number to the file format. Of course, the world doesn't care about any of that, but I learned something doing it and am happy about that.
Designing things yourself is enjoyable and educational, so that is also a good reason.
The flipside here is that keepass format has passed quite a lot of scruitny over time, so the design should be pretty decent at this point (especially from security perspective). All that complexity that might feel overwhelming at the beginning also gives you room to grow over time.
As long as your code is well architected and your featureset somewhat conservative, switching out the storage layer shouldn't be too difficult if you ever change your mind. So from that perspective it makes sense to keep going with your own format as long as you feel like it, and focus on more important things.