I don't know if the normal SVN distribution has that feature
It does, that's the normal way of SVN branch merging.
but if it does, then I don't see any big troubles with merging branches into trunk when needed.
Consider the difficulties when you have conflict with one file. Multiply it by the number of files
you may have deleted/modified in your branch, and by the number of files all the other
developers deleted/modified. If we do not merge very often into the trunk, that's what we will face.
And if we do merge often into the trunk, we don't need one branch per developper.
IMHO, using this system simply postpone each atomic problem (ie file conflict) into one
single macro-molecular problem (branch conflict).
Just know that I am not convinced of the relevancy of such a system for such a little
amount of developers; this paradigm has its benefit, when reaching hundreds of developers
working on unrelated parts of a very big project, such as the linux kernel or cairo, which rely
on another concurrent versionning system natively supporting this, namely "git".
Anyway, I will follow the final decision; if it is having one branch per user, so be it.
I am just not convinced