I was wondering why the button push is much better on my Aluminum Core than my last two plastic model Cores. If you look closely at some of my pics, you can see a stainless steel collar that surrounds the buttons as they protrude from the aluminum watch case. The buttons are set in like a piston. This collar is not on the plastic Cores and can only be found on the Aluminum or Steel Core. This could explain why the button push is noticeably better. Interesting.
This is a pic of the Regular Black and Observer. The case is molded around the button instead of a collar that the button rides in like a piston.