Yes it kinda sucks that they're closed source, but it's just so neat and works so well across devices. And the community plugins makes it super versitale.
What lets me sleep at night is that even if something ever happened to the company behind it, the AppImages aren't going away and all my files are plaintext I can read with whatever I please. I'm also not relieant on their sync service so nothing would change for me despite not getting updates.