Said that, did you ever try to mix in mono? One thing you have to keep in mind is that even if your mix is good in stereo it should be really bad in mono. Why is it important? Because if everything is in the right place in mono it would be simply great in stereo, in every system you’re going to play your mixes (iPod, big Hi-Fi systems, laptop speakers…). Let’s do an example: if a listener is in the middle of a stereo Hi-Fi system, he will catch for shure the wideness of the mix, but if he chage room during the listening, he will loose everything about the right-left placement! He’s definitely listening in mono.
That’s why it’s really important that you mix in mono. Because listener will listen in mono, even if it’s weird, but it will happen! If your mix is good just in stereo, your mix is not good. You can find a lot of plugin (that you have to add to your master bus) to get a mono listening. Some DAWs (like REAPER) have a “mono button” directly on the GUI.
Just trust me: if the mix is perfectly balanced in mono, it will be awesome in stereo!
This is a video by Graham Cochrane (I really learned a lot from this guy, you should follow his blog!) on this topic: