Hey @EdwardLouis I've been using Cascade for 8 years, even when there was UDK (old unreal engine). I recently started switching to Niagara and I have to say that there are many similarities between Cascade and Niagara. In any case, a lot of "transferable knowledge".
Niagara has many additional functions and options. I've examined some of them, but definitely not even scratched the surface. It is definitely worth investing time to learn it, as it will replace Cascade at some point imo.
In terms of Niagara and production, I haven't used it yet, but I will push for it as soon as possible. The only problem I've had with it so far is the LOD system because I can't find it in Niagara Otherwise no problems.