I made the switch today after testing Manjaro KDE out in a VM for a few days and installing all my software etc. The install was quite quick as my data already resides on a separate partition so no need to backup and restore 100GB+ of data.
Manjaro is based on Arch Linux (a rolling release distro so no major updates needed) and I chose the KDE desktop as I regularly use digiKam and KDE Connect and these are already baked into KDE. Interesting too that Steam games was already included in Manjaro’s base install. Manjaro is much like what Linux Mint is to Ubuntu. Arch Linux can be a technical challenge for many to install but Manjaro made it really easy.
So key differences I’m finding from Linux Mint:
1. No DEB files to just click and install – so far I have been fine with finding apps in the Manjaro or AUR repos, and other apps like Calibre just install as usual.
2. No PPAs – Ubuntu and Mint are known for the PPAs but they can cause clashes and create problems.
3. Rolling release updates – I won’t need to do a complete update anymore with major version releases.
4. Instead of Synaptic I have Octopi and Pamac repository managers. I am much preferring Pamac because it is easier to see what repos are being used.
5. KDE Connect – this broke on Linux Mint as it missed some vital KDE component. Glad to have this integration with my phone again.
6. Kernel manager – very easy to install newer Linux kernels on Manjaro and to switch between them.
Otherwise the apps and the themeing etc all works like before. Only had Manjaro running a few hours now but I am loving it. More info on Manjaro at https://manjaro.org/.
See photos from my install at https://www.flickr.com/photos/dvdmerwe/albums/72157682143440994 
Manjaro KDE Linux
Some screenshots of my install process. Manjaro is an Arch Linux distro.