I've had experiences with both leather covers and silicone. I've found out the edges of the leather cover over time can start to dig into your face (it's never something you notice at the beginning of the play session). The silicon is much better in all respects including price from personal experience. As far as maximum comfort goes not having something that presses on your nose is also good for when you don't need light for the guardian system (turning the lights off in your room so there's no light leakage issue).
Thx bro. I just ordered the two pack grey and black. One will be sacrificial where I'll experiment cutting the nose flaps off to make it as comfortable as possible and in case I totally screw something up I'lI have the backup.
One of the reasons more specifically why I think the silicon cover is more comfortable might be because it not only has a bigger surface area touching your skin (which means less pressure) it's also softer from the material that's directly touching your skin to the foam or fabric stuff behind it. I'm telling you the edges of the leather type that I have used eventually start digging into your face!.