Hey Bruce
Don't know if you are still looking at Precision Mathews, or even column mills of any brand, but since you started this thread, I've been looking around at what's available and comparing it to my little Grizzly mill. I am still perfectly happy with my G0704, but it seems like you have jumped up a level or three as you are now talking about an 1,100-pound machine it seems, and that is in a completely different class from what I have.
However, one thing I've noticed about PM column mills that would make me lean that way rather hard were I to be buying now, is the way that the column is mounted to the base on the PM machine looks to be much more ridged than how my Grizzly mill column is attached. Of course, being more ridged, does not mean that it is necessarily square to the table as received from the factory, but it does mean that once properly squared up, it is less likely to go out of square caused by taking a heavy cut or similar stress.
Just another point to ponder!