In my quest to find the best 
portable 88-key digital piano to control the Yamaha GENOS, I settled on the 
Roland RD-88.
Thanks to Frank Ventresca from 
AudioProCT.com for delivering the unit in pristine condition via UPS.
When deciding on a portable 88-key piano as a lower manual to control the GENOS, the two main factors are the key feel and the quality of the piano samples.
Keyboard ActionThe Roland RD-88 keyboard action trounces the competition as this price point. The Progressive Hammer Action (PHA-4 Standard) on the RD-88 with key escapement surpasses the GH3 action on the Yamaha P125 and the RH3 action on the Korg D1. 
The black keys on the RD-88 do not suffer the unevenness of the Casio CDP-S350 that I reviewed 
hereThe weight of the black keys feel balanced with the white keys as they should.  The length of the white keys comes at a standard 5.75”.
To make the black keys equally playable as the white keys the depth of the keyboard had to be increased to 10.1” compared to the slimmer 9” depth on the Casio CDP-S350. Yes, that 1 inch makes a world of difference
The height of the Roland RD-88 had to be increased to 6.3” compared to the shallower 4” height on the Casio to accommodate the PHA-4 mechanism.
The RD-88 weighs 5.8 lbs more than the Casio.
The slight increase in size and weight on the RD-88 translates to a much more satisfying piano action.
The keyboard feels very responsive. It is adequate as a portable 88-key graded hammer action controller that weighs in under 30 lbs. No other manufacturer offers a better keybed that weighs less.
However, the RD-88 features the most basic PHA-4 Standard variant. The next step up is the PHA-4 Premium followed by the PHA-4 Concert action.
The absolute best Piano Action from Roland is featured on the 
RD-2000. It has the top of the line PHA-50 action with real wooden keys. This adds a lot of heft. This weighs 48 lbs.
You can immediately notice the difference when you play on the RD-2000 after playing on the RD-88. The keys on the RD-2000 feel more luxurious and the action is smoother. You would have to sacrifice portability to bring the PHA-50 wooden keys to the RD-88.
The real wooden keys on the RD-2000 imparts an extra amount of inertia. This inertia helps in maintaining a finer control over the velocity with which you strike the keys.
Both the RD-88 and the RD-2000 feature synthetic Ivory toppings. They offer a better grip than the polished white keys on the Yamaha P125 and Korg D1.
Based on Piano Action alone, here are my rankings from best to worst:
1.
Roland RD-700GX featuring PHA-2 action with real wooden keys and key escapement.
2.
Roland RD-2000 featuring PHA-50 action with real wooden keys and key escapement.
Note: I am rating the older PHA-2 action as being superior to the new PHA-50 action.
The PHA-2 keybed has a heavier action more closer to a real grand piano. The PHA-50 action feels more damped and sluggish compared to the old PHA-2 action. This makes it harder to play repeated notes on the Roland RD-2000 compared to the Roland RD-700GX. The keys bounce back faster on the RD-700GX.
3. 
Roland RD-88 featuring PHA-4 action with plastic keys and key escapement.
4.
Yamaha Clavinova CVP-609PE with Natural Wood Keys.
Piano VoiceThe very first Piano Voice that comes up when you power on the RD-88 is the Concert Grand patch.
Typically, manufacturers place their best piano voice on the default patch.
However, the Concert Grand is not the best piano sample on the RD-88. You would have to patiently scroll to preset 024 = Expressive Grand
You can easily tell the difference in quality by pressing down and holding note C2 on Preset 024 and comparing that with Preset 001
The Expressive Grand exhibits a lot more richness and harmonics as the sound fades to black.
There is a reason to that.
This Expressive Grand sample was taken from the Roland RD-700GX Expressive Grand 88 Key preset. As the name implies, each of the 88 keys were individually sampled at multiple velocity levels. This is the piano patch that made the Roland RD-700GX gain its wide popularity amongst Stage Pianos.
Later I purchased the Roland RD-700GX SuperNatural Piano Kit. I was disappointed. It did not sound as organic and real as the Expressive Grand patch.
Roland has done a lot of R&D on their modeling technology. One can understand why they are pushing their SuperNatural pianos on all their newer products.
If you buy the RD-2000, their premium Stage Piano, it does not feature the Expressive Grand sample. Instead, you will find all their SuperNatural patches prominently showcased. You would have to be a former RD-700GX owner to know the existence of the superb Expressive Grand patch and find the download link to get this into your RD-2000.
The Expressive Grand based on traditional sampling trumps all of these SuperNatural samples.
This was Roland’s masterpiece. They are trying to underplay it.
Modeling technology still cannot match the subtlety, richness, harmonics and nuances of Sampling. 
This is clearly evident when you compare the best of modeling technology from 
PianoTeq with the best traditional sampling from 
GarritanAlthough both the RD-88 and the RD-700GX features the Expressive Grand sample, the RD-88 version does not quite match up to the richness of the RD-700GX. Part of the reason could be that the wooden keys on the RD-700GX offers finer control over the velocity bringing greater expression to your playing.
Outstanding Sounds on the RD-88Pianos
024	Expressive Grand *** This is the best Piano sample on the RD-88 ***
034	Expressive+Bell
Electric Pianos
066	FM Phaser
070	D-50 EP *** Turn on Dual Mode to layer the Staccato Heaven voice
Clav/Mallets
091	Vibraphone 2
092	True Vibraphone
095	Marimba
097	Music Bells
Organs
110	Rotary Organ 1
119	D-Bars 7
120	VK Organ 2
123	D-50 Organ
129	Far and Wide *** Excellent Patch
130	Cathedral
132	Accordion
133	Musette
134	Bandneon
Strings
140	Slow Full Strings
154	OB Strings 1
Pads/Choir
193	Kings Choir
205	Fantasia
206	Fantasy
209	Stacc.Heaven
The RD-88 allows you to layer any two voices that transmit on MIDI Channels 1 and 2.
You may also split the keyboard introducing a 3rd voice on the lower keyboard that transmits on MIDI Channel 3.
This allows you to play an Acoustic Bass on the lower keyboard while layering a Piano and a String Voice on the upper keyboard.
I will discuss the connectivity options in my next post.
Best regards,
David