Hi Gabor,
I don’t think any Seafile Rep. will say anything against using subst.
They actually point to using using symlinks in a different thread:
The problem with subst is not with Seafile, but with support from other software.
subst and symlinks for that matter don’t enforce their use. Any application has the ability,
to break through the substitution and access the real path. That’s the issue.
Example:
Real Path → D:\Seafile\Tom\My Libraries\Project
Substitution → subst X: D:\Seafile\Tom\My Libraries
When you access X:\Projects some apps will see and use
D:\Seafile\Tom\My Libraries\Project instead.
I’m using subst a lot and in my experience it mostly works. The only instance that doesn’t is Git.
Unfortunately that makes subst a deal breaker for me. But maybe not for you.