Greetings from Boston! I have a 2020 Duke. I installed the Coober ECU, de-restricted airbox cover and de-cat on mine and will never look back. The only other thing I plan on doing down the road is a slip-on.
Like mentioned above, not everyone has access to a dyno and it really wouldn't and doesn't make a difference to me. My bike is a frigging rocket. I'm not trying to come off the line every time fighting to keep the front wheel on the ground, it's not a drag bike and if anyone buys one of these with that intention they've missed the point.
With that, the Coober ECU works amazingly well. The stock 390 is exceptionally chonky off the clutch at 5 mph in traffic. It gets all chunky with too much fuel delivery. With the ECU all that goes away. You can take your hand off the throttle at 5 mph in first gear and the ECU figures out and corrects the fuel delivery so even in inclines it doesn't bog down, get chonky or stall. On the top end of things everything is smoothed out but far more responsive and aggressive when you grab a handful. I think my red-line/rev limiter bumped up 2500 RPM+ also.
The only other thing I did with this setup was to have the decat ceramic coated. I highly recommend spending 100 and having the decat ceramic coated. The radiant heat is reduced dramatically. Next winter I'm tearing the exhaust off and having it all ceramic coated. -it looks nice too, no discoloration at the header, no rust!