I'm not familiar with the Mackie monitors. A few years back I purchased a pair of Yamaha 5" HS50M Powered Monitors and I think they sound fantastic. I've mixed on other monitors, and prefer these by far. Very "flat" response, which is what you want, (the speakers do not favor certain frequencies, but instead give an even representation of what you're mixing).

The built-in power feature is nice in terms of keeping your setup simple; no power amp required.