Important to know Arq only runs on mac/windows but has an open source client for mac/windows/linux that can do restores. So if they go out of business your data isn't lost (presuming you used a cloud backup that still exists).

I left because Google's rate limiting makes them really slow.

Also they mix together all errors including permission errors and "the file is being accessed by another program" so every run will have a few hundred errors (in fact, if I got zero errors that always a sign that the backup hadn't run correctly).