You'd have to get into the Clavinova line to achieve that with Yamaha, in my opinion.
There is a 76-note Tyros 5, but same key action as previous models as far as I know.
There are some Ketrons that fill the bill.
The FSR action of the high end synths (montage) as well as the Tyros5 comes close to the G70 action...
The Roland G70 uses a Fatar 8 keyboard, so do indeed some of the Ketrons... The upcomming SD9 pro should have this high emd keyboard... And some new very high end piano sounds...
The strength of the G70 was its huge amount (300 MB) of sample ram in a time most other brand keys had like 80 MB... Its the same reason why currently the pa4x sounds are so detailed...
When i look at the orriginal question, i need to say the only instrument that fullfills the question is the Tyros 5, i dont think the good old PSR 9000 pro can be considered to have good piano sounds...
But if piano sounds combined with an arranger are your thing, you definately need 88 weighted piano keys action... There is only one keyboard thats enough arranger and has 88 keys while still being mobile, and thats the Korg Havian 30...
( there is also the yamaha cvp series, but they are far from. Mobile, but excellent pianos as well as top knotch arrangers)