It's nvidia's branch that was used in wukong and something else that eludes me atm, Epic are still focused on their own lumen and new things like megalights so don't worry about devs moving to pt and restir already it's still just nvidia balls deep in it. That being said megalights is actually a step in that direction and if they add a few more things to it, it'll be close to rtxdi.
The difference between full raytacing in wukong and lumen is around 30%, i'm not sure if wukong is software or hardware lumen but I don't think it's a clear cut PT murders performance and lumen doesn't.
I think we need to remember lumen has a cost, if you told someone lumen here was PT i'm sure we would get the not worth the performance hit arguments.
it would be really cool if someone got this running on nvidias branch so we could see the PT framerate. I would guess around 30-35fps making it about 25-30% heavier than lumen.