Ok, my cooled down and short take on this... ;). My apology for the noise.
There is little new about the 'New' Session Manager, it's a fork of
Non-Session-Manager, which is around since +- 2012 I think. So I'll just
keep calling it Non-Session-Manager myself for now, which saves me quite
some renaming on howtos and tips&tricks which I posted around on the
Internet as a enthusiastic user of NSM.
The new thing is the Argodejo GUI, I guess. So as a NSM user you've a
choice now between two GUIs for NSM.
The original one, which I think, is best downloaded from it's original
source, cause it's build with the NTK toolkit, for a better graphical
experience:
https://github.com/original-male/non
https://non.tuxfamily.org/wiki/Non%20Session%20Manager
(All though it's hard to get it in distributions because of waf, it's
easy to build luckily enough.)
And Argodejo, which I found here:
https://laborejo.org/argodejo/
My 0.02$