This ^^^^.
I have a spare 19RCS, and I put it on the 1299 to test, I can say, wasn't happy with the feel, it was stiff and I didn't have a lot of feedback under hard braking. It was almost too much on/off in the feel. I bought a 17RCS and swapped. It felt significantly better, it was still 1 finger stopping, but, I could get feedback from my Braketech CMC rotors, where I had no feedback from the 19.
The 19 will work, the feel is just different. you might change the pivot point to be the "red" side, instead of the white, as you will have a bit more feel. If it's set to white (20mm), which is what I rode on my R1, it was just on/off with a fraction of the pull. The 18mm setting (red), at least gave me a bit more feel.
I run the 17RCS on both the brake and clutch side with an Oberon clutch slave. It fixed all the issues I was having with the clutch and needing to bleed it every ride.
