Let's look at it this way. To unzip, zip, sit, or unsit files a mac user has to do nothing. He already has stuffit on the computer. To sit, or unsit a file a win user must go download and install aladdin stuffit expander which is a big waste of time. So we can obviously see who's inconveniencing who.
I prefer .zip over .sit personally. Mainly because I don't have to worry about whether or not somebody can open the archive. Nearly everybody can open .zip these days and most people don't want to pay for Stuff-it just to open the rare .sit file. (PC users that is.) Basically: Go standard file formats!! Go Mac!!
