Why would you bother switching out the 8 bus for a Ghost? Seem like a step sideways instead of up. The ghosts are renowned for being noisy, and inconsistent. The Mackie is just clean and colourless. You probably have a rack full of outboard colour going on anyway.
Tom. I own a Ghost and it has proven over the years....(I have had it for 10 years now) to be none of the things you describe. The Mackie is a flat, lifeless, mixer with very little headroom on the pres and an EQ that can best be described as a "tone control" rather than something that could be 'surgical'. That being said, the Mackie is a nice platform for routing in a digital studio and is a very very good portable mixer. But holds no candle to the sound of the Ghost. That being said, there are seriously better consoles at the price available than the Ghost and certainly the Mackie. However, the upgrades available for the Ghost will put it in a much higher class of mixer even to the point of making the pres on a par with most mid and higher rack gear. Not saying it becomes a Neve or API or even a Manley, but it becomes a very good sounding console for the footprint. The whole board upgrade effectively doubles the new price of the Ghost but more than doubles its effective use as a recording device.
I use mine primarily as 'overflow' pres and routing for headphone sends and adding effects in the phones as well as the front-end for my Alesis HD24 recorder. I also have a PT rig and its here that the pres in the Ghost get used for only drums and incidental sources. They are, however, really good for drums and sources that require a fast responding mic pre with good transient response. Something the Mackie lacks in completely.