Can’t comment on arq6. It was very short lived, electron based UI, experiment. Not even a contender. It was rightfully scraped shortly after.
I doubt it had anything to do with a backup tool. Any backup solution is as reliable as underlying storage. On the other hand, with encryption enabled with any tool, including Arq and duplicacy, there is no way for you to end up with bad data even if storage rots. You either get back exactly what was backed up or nothing.
There are two factors that affect reliability (assuming your ram and cpu are working correctly): storage and networking.
For storage it’s easy: Use reliable storage that guarantees data consistency. Repairing data rot is a job of a filesystem, not applications. Datastore corruption is an impossibility.
Duplicacy does support erasure coding, so it can tolerate some rot — but the problem is, if even one byte is allowed to rot, who is to say that it will be limited to that one byte? Ultimately, the storage either guarantees data integrity or it does not. In the former case you don’t need to worry’s about corruption. In the latter — you don’t have any guarantees, so don’t use that storage.
The other factor — resilience to network interruptions — is indeed important, and both tools handle it very well, according to my limited synthetic testing and years of use.
Performance is never a selling point of a backup tool. It’s simply irrelevant. Yes, duplicacy is very fast, which is nice, but I take CPU throttling over any super-speed backup utilizing full resources. There is no reason to hurry up to finish backup in 5 minutes to then wait for 12 hours for another backup.
Duplicacy benefits from a very fast regex engine, this helps a lot with scanning when exclusions are specified. Arq5 used to be very, ridiculously slow for the reasons I did not look into. I don’t know about arq7, because I no longer use manual filters. Everything gets backed up indiscriminately.
This statement applies to any piece of software on earth
Arq 7, sometimes, does nothing for hours, no CPU load, no disk IO, no full RAM, then it goes back to its slow speed until the next shutdown
Have you got to the root cause of this? Apps don’t just do nothing, when they appear to be not doing anything with all stacks idle they are likely waiting for some asynchronous request, network, or disk IO. This is not specific to ark or duplicacy or Microsoft word. Nobody inserts delineate delays in the code