I was wondering when you would get back to it, finally you did
thats one hell of a model

It really is very good! I attaced an image with the only things i could find.
Red: you have some really smalle bumps there, should be not to hard to fix

Blue: the mat is very grainy, i don't think it should be that way. but well it's still a test
I really hope you have the motivation to finish it because you have an amazing project here, a project you don't see every day and you're doing it superb!