I've done this also. I have found it buggy though. About once a day the volume and brightness section stops responding until I do a restart of the machine. I assume this will be fixed in an upcoming update.
I have had the same issue. Buttons seem to just disappear on the touch bar randomly. If you press on them, they reappear again. Definitely some bugs with it.
/System/Library/CoreServices/ControlStrip.app/Contents/MacOS/TouchBarAgent