But is it worth the jump if both digitals both have the PHA-4 Standard Keyboard: with Escapement and Ivory Feel action?
Not action-wise for sure. 😀
I'm only interested in the piano sounds btw
They have basically the same piano sounds, so no real upgrade there either.
So the only thing you'd get is the different cabinet, maybe better speakers, more non-piano sounds in the RP-501R and some more built-in features not relevant for pure piano playing.
Doesn't seem to make much sense.
Also open to other brands/models up to the price range of the RP-501.
It's about $1600...1700, assuming USA prices.
There are a lot of models available for that money or less, but not many of them might be an "upgrade". It's actually difficult to say.
There's the Yamaha P-515
for about the same money. It might be a little more with the whole furniture stand + triple pedals setup, probably around $1700 is the listed price. (Plus tax? I'm not used to USA pricing details.)
The Roland FP-90 will be over $2000 as a complete package. But it would have a different key action.
Around $2000 there's Kawai CN29.
At $1900 there's Kawai ES920 full package.
At 1800 there's Roland FP-60 with the same action, so no action upgrade.
Also Kawai ES520 complete bundle is about that amount of money. It could feel lighter(?)
There's also the Korg G1. But would it have any benefit?
Casio Celviano AP-470 is about $1700, but it could be just "different" and not necessarily "better" like many of the others. The speakers might be better and the action lighter. I'm not sure.
Yamaha Arius YDP-164 can be had for $1600 or so, I guess. But again, it's "different", but is it "better"? People tend to say the GH3 is "heavy".
At $1600 you also have the Korg C1. And the Kawai ES920 with no extras like a stand of triple pedals.
Others might have some opinions on those models.
And the prices are just a rough estimate.