Hello André. Yeah, I'll second that - I love it too. I can already shift up OK at higher revs, but have been extra-cautious about rolling the throttle off, changing, then rolling it back on, to get the feel of things.
In reality, there's not much need to roll it off too slowly, as long as it's not opened up again too quickly. I've been taking note of the slight take-up when the pressure starts to go back on the rear freewheel cassette. You can feel when it has engaged properly.
As you say, a bit of practice.
I need to get used to selecting the right gear as I slow down, too, since you can't feel it with a freewheel and want to be in the right gear when you accelerate again. Getting better at that.
I'm finding that part of the fun is learning the technique, and I always did like clutchless changes on dirt bikes.
... Steve