Jonathan:
The effect of engaging a Q is a little similar to the bright switch in that the Q will emphasize the most high end portion of the frequencies the LPF is letting through. The 3-way Q lets you employ more subtle changes, (0-6-9 db boost at the cut-off frequency), than the bright switch. I, too, tend to find a sweet spot on the LPF and leave it there. I usually put my Q in the middle position, 6 db boost. Then, as I'm playing, if my signal sounds a little muddy or bassy, I just hit the Q to the 9 db setting on the fly. Conversely, if my tone sounds too shrill or trebly, I hit the Q the other way so there is no boost at the cutoff frequency. I certainly use my Q switches far more often than the bright setting on my Further. You can still open up the LPF all the way and switch the Q to the 9 db setting to get that trebly acoustic piezo tone. If you otherwise seldom use the bright switch, then, it seems to me, a Q is a no brainer. As the old Alka Seltzer commercial used to say: "try it, you'll like it".
Bill, tgo