Supporting multiple devices with one design

Pin assignments can be changed quickly by sourcing a tcl script. So if you get your project set up for device A, then close the project and open the .qsf file and just grab the set_location_assignment lines and save that to a file called pins_for_A.tcl for instance. Then do the same for device B. Then, right before you compile, just open a tcl console (alt+2) and type : source pins_for_A.tcl and then hit compile. If you wanted to get really fancy you could customize your toolbar with a tcl command button that sourced the file for the device you wanted to compile for.