DavidR, you can always hide the application so that the window won't take all your screen estate. The dock will keep showing all details happily.
But I agree, I have suggested a while ago to have some sort of minimised state, so that the entire big window could shrink to a small window with stripped-down information.
Kairos is one of those apps which must be running all the time (otherwise what's the point?) and it is in fact on of the two reasons why my Mac at works is eft on permanently (the other being Timbuktu).
It's a great app, once a less intrusive display is introduced (either, as you suggest, by embedding the data in the menubar, or by having a small floating window) it will be just perfect.