So the Soma Fab shop seems to show the IQ-XL 300 lux headlight in stock for $329. I put it in my cart and it didn't complain. It's also on the Merry Sales website (same company). If they have it, I wonder why Peter White doesn't. Merry Sales says if it's not in stock, you can't add it to your cart. It let me add it to my cart.
Anyway, I liked this bit from Peter White:
In low beam, the headlight is rated at 300 lux, the brightest dynamo powered headlight ever! That's three times as bright as the IQ-X. There's a handlebar mounted switch to change to a high beam. At high beam the brightness rating drops to a mere 250 lux. ;-)