I finally got around to using dispcalGUI to profile my monitor under Linux. Now, having assigned that profile system-wide using Gnome Color Manager (or the Xfce Color settings dialog), there's a visible change in on-screen rendering (including any open Gimp windows).
Having done, that, should I also go into Gimp's preferences and enable the profile there? There's a "Mode of operation" setting, which has "Color managed display" as an option, and then below that, a place to assign a monitor profile — include a checkbox for "Try to use the system monitor profile".
Should I turn these options on and check the box, or is that "doubling up" where I shouldn't be?
(If I do check the box, there's an obvious change — the colors become brighter and more saturated. But I have a hard time judging by eye which is more accurate.)