I've used this since I've first owned Pianoteq, it sounds good with all the acoustic pianos in particular, esp the D4 and Bluethner, and more recently with the latest version of the K2 Grand. I'm a jazz player, but like a rounded tone as opposed to a sharp or piercing tone some pianists prefer.

Velocity = [0, 1, 9, 35, 64, 127; 0, 0, 40, 64, 96, 127]

I tried this curve, it felt pretty aggressive, which curve are you running inside the RD300 itself?
Here's the curve I'm using in Pianoteq:
Velocity = [0, 23, 53, 75, 95, 115; 5, 24, 69, 98, 117, 127]
and the RD300 is set to Medium curve, zero offset

Velocity = [0, 1, 9, 35, 64, 127; 0, 0, 40, 64, 96, 127]