I'm using Debian Testing with KDE, after using Ubuntu with KDE, and it's basically just some lack of polish, and I also sometimes miss the PPAs. (I understand that it's technically possible to use software from Ubuntu PPAs in Debian, but as I'm getting older, I prefer officially supported ways of doing things, so that I can stay on the happy path as much as possible.)

So all in all, not much of a hurt, for me at least. My home server integrations, my software and my games work just as well.