I'm so glad that work is being done on session restore on Plasma. So many of my issues with Plasma have been fixed over the years, but this one has always been a big showstopper for me.
Kwin crashing and taking everything down with it is not something I want to happen on my work machine. Most of KDE's bugs I could deal with, but not that one. Losing hours of work is an absolute no-go.
Session restore is probably the biggest thing that I've been looking forward to for Plasma 6
I'm still not sure it'll become the desktop I'll use all the time, but I'm wanting to give it a try again to see how it goes.