I think it is good idea.
Of course it would be better if they started at the right level, and we were allowed to pick traits. Failing that, it is much better to start at level 1, so that no traits or worse, a path, is lost.
Let me remind people why this is necessary:
At the present built (.983) when you train a henchman at a fortress, they get the fortress bonus level, but not the traits for it. If your fortress trains level 4 units, your henchmen will never get a class, i.e. will be quite useless.