Just an update, I've installed the 180mm Debonair air spring (with newer C1 Seal Head) into the Yari. Quick and cheap enough to do. A few observations after two laps of the local loop (~24km, mixed riding with some technical ups, burly downhill sections and fire trail/roads).
1. The fork easily sits 20mm higher than it did before, 10mm in additional travel and ~10mm due to the new C1 seal head. As such I dropped my stem about 12mm in the stack. I'm a heavy guys, run 90-100psi usually on the front, but dropped it to 85psi - and blew threw most but not all of the travel (typical for the trail).
2. Downhill felt great (same or better), though I'm unsure whether to attribute this to the 10mm more travel, or the the new seal head. It's hard to judge as last few rides have been on my analogue Reign 29.
3. Uphill felt the same, and the loop includes some steep technical ascents. Front end felt planted and was not poppy.
Overall seems a positive mod, though I'm keen to get it out on some more serious downhill and jump lines. If anything, the rear end seems the big let down, I'm just awaiting on a super deluxe.
Regards, Damien