I've got the Ixon IQ as well. I've got mounts on all three of my bikes:2 with the Minoura Besso (not for carbon forks) and one on the bars...the 2 with the Bessos mounted mid-fork cast a much better light.

B&M sells a fork crown mount (the wire model not the all plastic one) that may work with caliper brakes. and depending on how much clearance you have below your bar bag may work for you. The Paul stemcap mount probably won't clear a bar bag, unless you have a stem that points down quite a bit.

That leaves extensions to go above the bag or a skewer mount or the NOB. Really the NOB isn't rated to handle heavyish battery lights and I wouldn't trust it considering the price of the Ixon IQ. Going above the bag can block view of your cue sheet and it really will affect how well the beam projects on the road. Skewer mount would be the next best after a mid fork or fork crown mounting option, IMO.