I think it would still be nice to have some form of HammUER for source 2. After about 3 months with new CS2 Hammer editor i can export FBX's and work with them in UE but my biggest troubles is dealing with the texturing. I find the biggest workflow is getting it all auto textured. Not sure how possible it is with everything being a mesh now but its been a lot more tedious editing the textures in the data with Blender plugins.
HammUER 2.5 slaps too much to not have but the new Source 2 editor is so good as well. My main project i am keeping on Source 1 to use HammUER but wanted to show my interest in it if it could ever be a possibility in the future (even if thats paying for a new plugin for Source 2 instead of an update)