I have the Pro. The Sheath weighs 14g more than the Apple Silicone.
When I first got the Sheath I was switching between the Apple Silicone because of the weight. Then one day I said f it, I’m going to run the Sheath no matter what. Then I got used to the weight. Now it’s no problem.
IMO the Sheath aligns second best when it comes to form factor. Curved smooth edges to the back, not boxy.
Here’s the specs of the Sheath and Apple Silicone. As you see the only difference is the depth.
Sheath
153.6 x 75.9 x 13
44g
Apple silicone
154.4 x 76.5 x 12.1
30g