I just switched to using cura directly instead of inside of repetier host for some of the printers I run. I prefer to use Simplify 3d when I can, but the license I have access to is on a couple of computers in a lab that has classes in it. Cura does the job for most of my prints, but the results of simplify 3d are simply better and support is a breeze to remove.
As far as build volume, something the size of a mpcnc would be a nightmare to try to print ABS reliably, but pla would be super easy. That being said, I saw that someone has recessed a heated build plate into the table of a mpcnc. A well tuned ultimaker can reach about 150mm/s where as my tinyboy can reach about 50, so I can understand the want for faster printing. Someone here has an i3 with an e3d volcano on it for super fast printing. Of course you sacrifice the layer resolution.
I am in a similar boat as Jon. I am almost done printing parts (just the middle z stuff left) and I need to start thinking about build size so I can buy the correct amount of conduit. I think I want 2’x2′, but have no clue on the z. I will be using it with a dw660 for routing, but also want to use it as a printer. I currently feel limited with the 3.1in height on my printer. I think I would like about 5 in of space for printing.
Would having a different set of legs help? So I would have a taller set for 3d printing so that I can get maximum z height, and then have a shorter set so the x and y axis are closer to the work surface thus making the spindle closer to the x and y axis. Actually, it would probably be more like blocks to put under the feet to lift the whole machine up for taller prints. They would have to be secured to the table of course.