I've been using Snapz Pro for some time and it's easy to use for screen grabs and the like. However, I dislike the fact that its installation seems to do some weird things to the OS. Other reviewers have noted that it messes with kernel extensions and the like. After installing Snapz Pro, I decided to only launch it when needed rather than have it as a startup item in my login file. Curiously, this seems to subtly screw up the loading of other OS components. e.g., com-shift-4 for screen grabs will now not work plus some items in the menu bar (on the top right corner) don't seem to always load at startup. If I launch Snapz Pro then all the icons on the top right corner of my menu bar reload. Considering what Snapz Pro does, this seems to be intrusive on the OS in general.