I am not going to pretend I know it all or that I am right, but from what I remember can share:
cPanel backup is a tar.gz (it requires you to restore the full account) (fast restore as restore is copying a big file to the server and restoring it locally). I remember someone saying how good this option was as it is fast on restore.
A very bad thing about this is that every backup will push a full account .tar.gz to the backup target. It is super very slow on big accounts. Also, the Production server is under a bit of stress when backups are created. Also, a lot of bandwidth is used for transferring the backups every night. (this is a no-go for my personality) i care more about my production server being available and using the least bandwidth possible.
Jet backup was created around cpanel and other panels to allow differential backups on various targets. (the restore is slower as it is moving file by file) it is granular, and it can be faster if you know what you want to restore. You can restore only a few needed files, but it can be slower if you restore a big account with a lot of very small files
Enhance it is using a jet backup-like, (almost as at this point in time can not restore a few files only) system, and the benefit is that it can be installed on very cheap hardware and can be improved in time. And with a bit of effort, enhance can beat both previous systems.
At the moment (enhance backup) it is a differential backup, and files are moved one by one.
What can happen with a bit of effort is:
Keep and improve the differential backup.
Improve restore options by:
If a Granular restore is selected, you restore file by file. This is the path that Enhance already took.
If the full account or full Server Restore is selected, then the backup server should locally create archives and deliver big payloads for fast transfer.
This would make any other backup system obsolete. And stop the backup system war 🙂
At the same time, S3 or B2B can not compare on price with a Hetzner or OVH 4 x 10 TB server for 60 Euro price.
Dedicated servers are super affordable considering the price/tb.
It is Ok to be a fanboy of S3 or B2B, but if you do the math it is impossible and actually futile to go that path, but i am not against it, as I am not wasting my time creating tools for s3 or b2b or any other storage target.
Yes, there is some work, but with the correct direction and do it once do it right attitude, we all can win from it, fast.
If the above is wrong (it will not be for the first time 🙂 ) take only what is good, and filter the bad.
If this is possible (Adam can confirm), and if you read this and like the idea, vote it up. 🙂