Wall of text, you've been warned.
I haven't been involved in producing casts outside of an occasional lan due to life and burnout. But the occasional UGC casts I got to do were some of my favorites, because it was a break from the norm, it was a break from having to figure out which matches RGL was gonna cover, or having to deal with the shenanigans of invite players being late to a casted match. With UGC, it was easy, hell most of the time it was literally just Brock asking me if I wanted to produce a match or me being bored out of my mind. But at the same time, casting Ultiduo was chill as fuck, not having to track 12 different players simultaneously, or 18 if highlander(yes that's even including cheat feed). Despite it's decline at the end of the day UGC ran seasons of smaller size formats that don't normally get attention outside of the occasional cup. It always felt more chill than RGL.
The pressure was always there though to focus on RGL, whether told to or not because that's where all the top players were playing.
Don't get me wrong, I know UGC has a bunch of issues it needs to resolve, I still laugh occasionally about Ramen Gate*See edit. Hopefully this break can resolve most of this stuff and they come back. As a producer it was always nice to know I had casting options that were more laid back.
*editing to add that Ramen gate was not the tf2 side of things, still funny.