Blueprints are supposedly around 10x slower than native C++ (though this might have been optimised over the last couple of engine releases, not sure). That said, the actual gameplay logic forms only a very small percentage of the total workload, given that the heavy lifting for rendering, physics, collision detection and so on is all done natively, even if some of the functions are called from blueprints. To be honest, you’d probably struggle to actually notice a significant drop in performance unless you’re doing some seriously complex stuff in blueprints. Personally, if you prefer blueprints, I would stick with them 
I prefer C++ as I do a lot of programming in my spare time but it’s purely a personal preference rather than any practical benefit over blueprints.
Anyway, I have to say that video is one of the few to really give me a chill. If you need anyone to do playtesting then let me know! Looking forward to more updates.