It would be nice if TP109 makes some tests of synchronization programs. Once I considered making a comparison of all the synchronization programs which had been discussed here but I discarded the idea because for me it would be an arduous task.
I have never tested Zback very thoroughly because to this day I have mainly relied upon FreeFileSync, DirSync Pro and FullSync. I don't know how many profiles can be added to Batch in Zback- the window where .bal files are displayed is small and I am not sure whether it would become scrollable when it is filled with profiles.
That would be a big task. The more options apps have, the more difficult the test design, and many sync apps have lots of options. The results would also need to be timed and verified, and a single option setting can easily invalidate a whole lot of data. The only way I would consider testing sync apps would be to severely limit the number of apps tested, and selecting what apps to include or exclude would be a task in itself.
The apps I personally use for everyday sync jobs are Zback and Dsynchronize, but mostly Zback because of its highly configurable batch option mode. Zback is small, accurate and easy to use once learned, but it's not for newbies and does take some effort to learn to use it effectively. For detailed or specialized backup and sync tasks, I mostly use command-line tools like Robocopy, XXcopy and the like. For synching really big directories, say those of over 1GB, apps like Zback and Dsynchronize don't cut it and mostly crash or choke. For large directories, apps like FreeFileSync are much more efficient. Although FreeFileSync has its issues, it can sync large directories quickly without crashing or freezing, although I'm unsure how accurate it is. In any case, I use of FreeFileSync and similar apps such as Bvckup2 for syncing large directories of non-critical data.
Back to Zback. No, there is no limit to the number of profile (.bal) files. Yes, the profile window is scrollable.