Whether CG or miniature the flaw with many of these scenes is that the actor is walking through an environment that physically never existed at the correct scale, and no amount of compositing can truly make it look like he is standing there. In the case of Kamino, there are dozens of shots where it's clear that they didn't even build the floor or rudimentary props, it's pretty much just Ewan wandering in greenscreen land. By all means, digitally extend a set through CG or miniature work, but if you try to insert an actor into an entirely non existent environment you'll have a hard time making it work. What I will say is that I am aware of a lot of the model work that went into these films, particularly in Episode I, and I have to say, in Episode I it looks really good. I think that has a fair bit to do with the fact that it was shot on 35mm, rather than the proto digital cinema cameras of epII and III. I'm pretty convinced that a large part of the 'it looks too cg' complaining of the prequels comes from the sterile look of the unready format. Ep I had a nice warmth to it's photography a lot of the time, especially in the scenes where it's mostly real set and props.