I don't think it will be really affective. The pin surface that touches the base is only very small. And I think it's just that connection that is the limiting factor these days. As you can see many blocks only have 6mm high fins or pins or whatever. That's because it's the optimal spot for the lowest possible deltaT with certain flowrates, that's also why a certain base thickness is optimal.
I think that with your design it will not be a very good block with a medium to high flow through it as explained above. I do think that with very low flows (say without a pump) tree fin blocks can be pretty efficient, but a maze design can never be efficient in a passive loop.
And you really have to think about the holes you want to make in the fins. I think there won't be any flow trough them and they will only be trapping the heat.
Sorry for this negative comment
