If you do upgrade to the Ceado or something else, please report back on your impressions. I'm actually pretty happy with my F4, but perhaps I don't know any better.
Given the types of beans that you prefer, I wonder if it would make much of a difference in the cup; although, workflow and ergonomics may improve. It seems like the lighter roasts and more esoteric beans tend to require the high end grinders, more so than forgiving blends like Redbird. I could be wrong, so hopefully someone will correct me there if needed.
Even when pulling lighter roasted coffees, I can't tell the difference between my shots and those at local coffee shops with the same beans. I found that turning down my brew pump pressure helped with that.
What is it that you're trying to fix or to achieve though? That may help others to fine tune their recommendations for you.