Hi Rafael,
"The new Change Width Node doesn`t seem to work with Redshift. I`ve tried the Latest Stable version and also the nightly build with Redshift v2.5.52 and I can`t make it work even on a new scene applying fur to a sphere."
This is because our new ChangeWidthNode is not fully integrated with Redshift yet, keep using RenderSettingsNode to change the thickness of the hair instead. RenderSettings is not in the shelf anymore but you can add it using the follwing MEL command: OxAddStrandOperator "" "RenderSettingsNode";
"Also, the Hair density seems to break when I use IPR rendering. I mean, the IPR shows only the viewport count and when I try to render again without IPR the density only shows what`s in the viewport."
We are aware of this, this is how it is suppose to work for now. You can render the final hair (Render Count) when doing a bucket render (non-IPR), for IPR you have to use 100% hair in viewport to be able to see it all in the render. This will change in the future but we will have to wait. :)
Jeordanis Figuereo (Product Designer. EPHERE Inc.)