How a dp works:
- There are three sensors that sense the motion of a key and pass this information on to the software which then tells the piano to emit a sound. As I understand, they are sort of like on- off switches, and the third tells the piano how fast the key is traveling from point A to point B which translates into loudness. Where those sensors are located can have an effect. If your key has to travel almost all the way up, and almost all the way down, in order for the on-off to engage, then you can't play repeated notes as fast because of the huge travel you have to do.
That is true.
And the username checks out!

One can see the various effects most plainly when comparing waterfall Hammond-style semi-weighted actions (I think those are all made by Fatar, including in the Hammond-Suzuki keyboards, but I could be wrong: I still use a Hammond-Suzuki XK-1 for organ, often MIDI'ed to the weighted piano for the lower manual. Not ideal, but it's a compromise which fits my needs), which have a trigger sensitive to a really shallow depth.
In other words, towards the "top" of the key. It's not a simple verkakte spring-weighted "synth" action, but it's in the same ballpark, and it's a good balance between the resistance on a real Hammond organ (which is mechanical in nature) and how one can have had it reproduced with modern manufacturing. Very easy to trigger fast repeated notes, by just adapting to the trigger at the top of the key travel.
However, on the Yamaha graded hammer action (yes, I know they've made quite a few advancements in their latest high-end offerings), the trigger is very much at the bottom of the keybed.
It's almost as bad as the electro-mechanical Rhodes piano.
That said, I find it pretty easy to do single-note trills on the Yamaha action. It's not ideal, but maybe 80% of the way to a proper piano action. Close enough for jazz, although I wouldn't want to use it for anything important in a concert setting.
I don't have a video recording, but it's more than adequate to do the K141 of Scarlatti at a pretty good pace.
It is a lot of wasted effort, though, using the forearms to adapt to this kind of chunky action: it can be pretty tiring to the forearms and shoulders, even using what I think is pretty good, if not impeccable, technique on my part.
However, it's always in tune, and while it's a bit of a chore to carry around in a case, even a light "gig bag," plus amp and speakers and all that, it's almost always superior to having to adapt to some beat-up "house piano." At least it's consistent, so one can predict.
Pretty much compromises and I'm resigned to just have these solutions be "good enough."