What is SD and SDC?
Well buy one, try one and see yourself.
Do you found liner locks much less complicated, just because there are less parts?
Consider the difficulties that are in making a good liner lock, things you cant see at first.
Well, even a badly made axis lock works the same way a good one does.
A badly made liner lock will not work.
You can even make the springs yourself. But imagine, how thin springs in watches are and how long they do. They are not as exposed as the axis springs? Yes, so lube them and you are fine.