I just implemented adx on a sub url of one of my websites. Adsense ends up taking 98% of all impressions.
This morning 5.4k Adsense impression, 300 unfilled and 5 adx.
Someone else did the original setup a few years ago, something about competing of Adsense and adx, I can't remember but if possible I would like to try only adx, no backfill from Adsense.
Would be greatly appreciated some insight.