I've been using LibreOffice for Loreshaper Games' design for a while, and it's just not cutting it. LibreOffice does pretty much everything we need, sure (I'm typing in LibreOffice as I write this, so you know I'm at least somewhat of a fan of it), but it's not necessarily designed solely around doing that. One of the issues I've been running into is that its overhead and performance are not great, and that while it has gotten much more stable than it once was it still doesn't like a lot of large images.
Combine that with some layout woes, and you have something that just isn't delivering when it comes time to put things together. The result is that the Hammercalled Quick-Start is not really what it could be. You just have to download it from DriveThruRPG to see that the half-page illustrations are just little things in the columns because I didn't have the time to go in and make them fit the half-page style, and even once I did I'd have to keep fixing them in perpetuity. There's also not a lot of happy text/image interplay; I'd need to basically add transparent text over whatever text appears or manually line up the text again, which doesn't help with making things look professional grade.
With the Hammercalled Quick-Start, I got around this by making the cover in Inkscape, then stapling the cover on in my PDF reader, which doubles as an editor. The problem with that is that it's not meant for a really hardcore document editing solution (or rather, it is, but not for what I'm doing), so this is never going to provide something that's print-ready. There's no real layer support, no color management (without jumping through hoops), a need to manually add it every time I do it (yes, you can use a command line interface to do that, but it would still add an extra step versus what Scribus offers), and generally it's just not a whole lot better.
I guess the short of this is that while I'm still doing most of my work in LibreOffice, I'm moving toward having more stuff get done in Scribus, because it offers a few features that are really nice regarding formatting.
The problem is that it is more work. Scribus doesn't support the automatic creation of bookmarks from text styles (at least as far as I know), nor is the Table Of Contents process as simple. This means more manual preflight stuff, but that's the price for looking good. I can actually get my PDF editor to do automatic bookmarks (yay!), and that would even fix some small issues that I was having with LibreOffice, but the TOC is going to be a major issue going forward.
There are still going to be things I do entirely in LibreOffice, like The Paradise Incident and the Hammercalled Rules Reference, but the need to be able to do increasingly complex tasks as my product library grows is pressing. On the other hand, moving to Scribus means I'll need more proofing and editing, as any system that goes from automatic and reliable to manual tends to be a failure point.