I think they would be good for hot weather. I tend to have hot feet when hiking. My feet stayed comfortable from freezing temps to mid 50s. They were also pretty easy to break in. I'm very impressed.
I have the Cabelas model. It offers plenty of protection as it is made entirely of thick neoprene, but is somewhat heavy. I haven't used the other models recommended on here but I'm sure they are lighter than the Cabelas offering as I'm sure it is 8-10oz. It fits very well on shorter rifles...
I read a description on another site that suggested each handle was permanently attached to a blade in a sealed bag. I'll see if I can track down the website again. It looks like a great alternative to the folders if it does have replaceable blades.