As for Pillars of Eternity there is one flaw with the comparison.

There are classes in Pillars of Eternity and the majority of your power comes from those classes. (I am going to ignore the broken/bad classes for this argument).

So how do you have cross classing be meaningful when there are no classes? Exactly what DOS2 is doing.

With what the Topic Creator has written up... Why even solo class? There is a clear super optimal route already written in.