Opened my 4.27 scene in 5 preview 1 and everything is working really great.
The only issue Im having is that I have some flickers with the GI in the Trees Static meshes
Im using the Blackadder trees from Megascans
Also Im using Unreal for rendering footage for production, not for gaming or RealTime visualization, so if there is a solution but will cost me performance, is good for me. I like that in UE5 I can render a frame in 1 min instead of 75 min with Arnold.