Haven't played or heard the older HP series, but I have 3 weeks now on an HP201, and the piano sounds in it just get better the more I play. Okkay, the more I do sightreading drills.. nowhere near playing chops yet
Dunno if the 10x does what I describe below. Have never even seen one.
What I like about the 20x piano sound: (this is primarily for Grand I, I barely use the other sounds.)
1. Has the hammer striking the string ('plink')
2. Has the damper hitting the strings after key release (a 'thud' with a little bit of the string's motions being very quickly squelched by the damper)
3. Has a ballsy, brassy, thundery, fiery bass -- the 207, with its much bigger speakers will really make this work.
4. Has a chimey, silvery mid and treble -- a good singing voice.
6. Has sustain-pedal-on resonance -- with all dampers up, the non-struck strings sing sympathetically with the struck strings. Say that 3 times fast.
7. Awesome dynamics. Very easy to get ppp, very controllable. At ppp very mellow, sweet. Step on it, and it gets very firey. Awesome control. Can't stress this enough. Completely unlike other digipianos I tried.
I'd buy the 207 just for the satin black cabinet, ivory-like keyboard with half-lid position (so it looks like a real upright)..
But dosh is tight, so 201 it was.
Can't say what the older PHA action feels like, but I can vouch for the PHA II action -- it's right scary. To my fingers, I haven't felt a more real fake piano yet. I measured downweight at 65g at middle C -- haven't measured upweight yet.. might do so tonight, while taking a break from more sightreading training.