I went from JB to KK months ago and run xposed for a lot of things. I am currently on Purity Rom but was on rooted stock. I haven't had any issues and have never said "wish I was still on Jellybean" to myself.
If you have custom recovery you can always make a nandroid backup and revert.
You will have to reinstall xposed and your modules but I use Titanium Backup and never had an issue.
If you are already using GB there is a version for 4.4.2 that's as good if not better. IMHo.
Rooted and installing Xposed the sky is the limit in terms of themes and roms.
Sent from Tapatalk on my Verizon NC5 Galaxy S4
Verizon Galaxy S4 - MJ7 - Safestrap Enabled Hyperdrive 13 Driven.