gster123, actually it was exactly what I was looking for. I duplicated my model with instance and then selected the duplicate and applied proxy with subdiv level 3 and subdiv transparency 1.0. Then I turned off Wire on smooth shade.
Now I've got a base mesh and a subdiv that updates automatically when I modify the base. Perfect!
Don't be satisfied with what you can do but rather strive to do the things you can't do!
Exceed Expectations!