I spent some time to experience the update, and everything seems to be more promising. It is now starting to feel like rekordbox 4 is actually out of beta.
I still experience latency on CDJ-2000. Although the latency has improved dramatically, I still notice a delay. It still doesn't feel as tight as what I expect with Pioneer touting the lowest latency (both Serato and Traktor feels tighter)
The CPU load is still unusually high. I am playing two tracks on deck 1 and 2 at the moment and rekordbox is using at least 80 percent in performance mode, and at least 50 percent in export mode.
I have activated my license for rekordbox plus pack, but the license key still does not display.