Hey JD.....
The Zytel scales are hollow to increase strength...... The strength in a molded part increases with surface area, or so I have been told by more than one expert..... That is why you see webs and such....... much easier and cheaper to make a solid mold for the scales but you get warpage and less strength...... This has always been a bit hard for me to get me tiny little mind to wrap around but, it seems to work out in practice... The molders art is certainly grounded in science and engineering but it has always had more than a bit of the occult among it's better practioners.......
Certainly the Micarta is more durable but, in thirty years there have only been a handful of polymer handle failures...... It is always amusing to me that the thermoset resin that is the plastic part of Micarta is the first practical plastic ever and it still excels in certain areas......
I love the look and of Micarta and sanded down almost smooth makes a really friendly and secure grip....... I like and use the Zytel much more often because, on a regular basis, I try to use "stock" gear so when I talk about performance I am not talking about exotics but what you all get in the box.......
I do occasionally use my "Sunday go to meetin'" blades with great pleasure but I measure my product's performance as they come out of the box......
All best...
Ethan