I have 2 printers. One has a 200mm^2 bed, the other 300mm^2. Each has its own Process in simplify3d.
However, the build area defaults to the larger printer, and will center on that one(150,150) which means parts larger than 100mm in either X or Y dimension will end up off the bed if I "Prepare to Print" for the smaller machine.
Selecting the smaller machine process does not change the displayed build area. Only if i go edit that process and save will it update the build area and center a part properly.
Selecting the smaller machine process in the 'Prepare to Print' dialog does not alter build volume or re-center the part for that machine.
I'm so far very impressed with the print quality from this software, but find it very behind Slic3r in its ability to deal with different machines.