U-turn was replaced by dual position, and I’d agree U-turn was great, as I thought the dual position options too far apart. I always found that you only need to drop the travel by 5-10mm to give you a more XC ride and more than that, you feel your pushing the front wheel into the floor.
Anyways, 20mm axle are few and far between, though you do get some older RS Rev’s still about with it (2nd hand), IIRC they can have there travel changed (internally) and aren’t overly heavy. Otherwise I think your looking at mainly 15mm axled options, any option to change your front wheel to 15mm? Allowing you to choose from the like of the Reba or X-fusion Slide