This is all about the selling you a "Device" and prices vary greatly between resellers. The devices work well, but the pure cloud solutions need a lot of work.
FreeNAS suited really well in managing our legacy systems and it handled all our network flows really well, less maintenance is required on our part. FreeNAS also gave the option to switch to TrueNAS for free as now its support is limited. The major issue that we faced was with the installation as it is really complex and required lots of time. Rest all is good and FreeNAS still works well on our systems.
SQL Backups just don't work reliably. For us, we lost all of our SQL data backed up through the CTERA Application process. Although the logs indicated a success, that was really not the case. This came close to putting us out of business. Luckily I had taken a genuine SQL backup to a folder. Unfortunately it was a month old. We had to pick-up the pieces from there.
Don't use it for file sync and share. There are better products out there i.e. anchorworks.com
Support sucks. Good luck with response time and answers that are inconsistent between team members. For example I had to rebuild a VM from scratch. When I re-installed the CTERA client It obviously thought I was adding another device. When I inquired to tech support, one member said "copy the old Data folder" (I still had the old VHD. That did not work). The other directed me to the correct spot to just change the associated folder. The turn-around time was over 24 hours for this simple fix.
Documentation, plenty of fodder but no real tech there.
Unfortunately CTERA does not stack up well if you want a pure cloud BDR. I have use iDrive and Asigra. iDrive has similar support and SQL backup issues. Asigra can vary widely in support and price, but the software is solid.
Before swapping to FreeNAS, we'd been using plan old Linux servers running Samba and NFS with ZFS storage underneath. This worked really well for our requirements at the time but required a lot of administration when new versions came along, or new users had to be added or drives needed replacing, and so on. FreeNAS did away with 95% of that work and does a much better job too.