I like Window Magician's concept a lot - sticky automatic window positions - but as it is, it's just a nerve-wreck to use. As Sgginc mentioned, entering coordinates by hand is a trial and error work I don't want to go through. It could have a simple button to record the current window position but then again, without the aid of another window management app, such as Moom, you couldn't save pixel perfect window positions (how to know if a window is centered on screen using Window Magician alone?).
Another serious flaw is the Title Scope preferences. As an example I wanted Mail.app main window to be a certain size and all new mails, replies and forwards to be a smaller size but still centered on screen (I hate newly opened cascading windows - open too many and they start going off screen).
They're all normal windows so I can't make different rules for normal/floating/modal windows in this case. So I made a rule to process windows with certain titles only. Now here's the flaw, what about handling dynamic window titles? Only "New Message" is static, all replies and forwards have dynamic "Re: xxx" and "Fwd: xxx" names. Even the main window shows "Inbox: xx messages" so it's always dynamic.
At the present stage, Window Magician works for a couple of apps but as previously said, trying to figure out coordinates by trial and error is something that makes me quit the trial after a couple minutes.
Other window managers lack what Window Magician has to offer and the opposite is also true but I'm not running more than 1 app for window management (something OS X should have by default).