Actually, when I send a script to collaborators, it’s sometimes hard for them to find Coder. Builder view opens by default (at least on the first launch) and they then have to use a menu to go to what feels like a distinct application. So having it as a separate app in the dock and as two different apps and entries in the start menu may actually be user friendly? Then Spyder could be a third. Also, when do they have to pass messages to each other other than just Builder instructing Coder/Spyder to open a file on the disc? Spyder updates instantly if a file is changed on the disc.
I don’t know much about running in same/different processes. But running Spyder and Builder/Coder simultaneously is not a problem on my Ubuntu 16.04. Subjects probably wouldn’t run experiments on both of them simultaneously 