Did it, it's fun. After I tried to pursue with Victoria 2, but there's a bigger gap between EU4 and Vic2 rather than CK2 and EU4. I lost my fun somewhere around 1860.
I dislike just one thing in conversion, it's about states and territories. You can't choose (or I didn't find it) which part of your realm will be state or territory. A bit frustrating, if you want to roleplay a big realm.
And I agree with Rashie, Charlemagne start goes to big empires in EU4.