milliput is great, if a little grainy
Totally disagree with you there. If you've got a grainy finish, something's up with your MP!

the GK one looks smoother than i would have expected from MP
It's my best example of the results you can get from shaving MP down once it's cured. None of this "smooth it down with a wet finger" rubbish. Leave it all bobbly and grainy, then use a scalpel to carefully pare it down until it's perfect. You wouldn't believe how sharp you can get the creases that way. MP and GS are totally different materials, and need to be treated in totally different ways. Try to sculpt MP and you'll do okay - do a basic bit of sculpting then carve it afterwards and you can get some great stuff. When you then sculpt fine GS details on top?

It's all about understanding the different properties of each material and adjusting your techniques accordingly.