Okay, im not entirely sure if this is the proper place to post this thread, but it is model related at least.
So ive downloaded a few models, but some are in s2z files and others are in normal zip files with folders inside. Some i was able to download both as zip and s2z. So what is the difference? And maybe more importantly - is there any performance impact by choosing one over the other? I was thinking in the line like the normal zip files with folders inside, when placed in the game / heroes directory they're already unpacked so might be faster to load, etc?
I don't think this is the right place to post, you would post this in the Modifications forum (you're in a sub-forum of Mods though)
to answer your question.
.s2z and .zip files are the same thing. You can rename a .zip file to .s2z and drop it in the Heroes of Newerth\game directory and you're good to go.
However, I find it easier to just extract them as files into the \game folder because it makes finding them easier for me. I don't think either one has an advantage over the other, other than the fact that a file would take precedence over a .zip (.s2z) archive if two things were conflicting.