I bought a new Yamaha P35 at an area music store for $450, which included a pedal to replace the foot switch that it came with, and figured it would be good enough to play on until I decided to get something better. I built my own adjustable stand using 1x8 pine boards, a 2x4, a 2x8, and some nuts and bolts. That was almost 10 years ago.
I played it nearly every day and after a year and a half, some of the keys started to make clicking noises. So, after removing 50 some odd screws, and unplugging 2 ribbon cables, the key mechanism was accessible. I purchased a tube of Super Lube, commonly used on RC cars, and with a flat blade screwdriver, I put a small amount of grease on each key guide and where the key contacts the lever for the hammer. The entire procedure, including all those screws, took about an hour. Not a click has recurred.
While I had the piano open, I noticed that the “hammers” were such that it would be easy to add weight, by taping a coin, or washer, or whatever, of consistent weight, to render the action slightly heavier, should one want that, and that modification, if done properly, could be completely reversed to original specs.
I might mention that the kind of music I play, mostly standards, ballads, easy classical pieces, and some original compositions, has never left me thinking that I was at all restricted by the mechanism. A third sensor, or half-pedaling, would probably be lost on me.
I rarely use the internal sounds, except when I just want a quick dabble, or to hear a thought in my head. Otherwise, I use virtual pianos.
As for the velocity of GHS, using either Pianoteq, Sonar, or GarageBand, I find the maximum value, without pounding a key unnecessarily hard, to be around 103 in the middle section, with lower notes slightly higher, and higher notes slightly lower, and all quite consistent.
The keys are not bouncy and the bottoming of the keys produces a reasonably quiet thump, not at all distracting, and really hasn’t changed since I bought it.
The keys are assembled in octave sections and are easily removed and replaced with a few screws should the need ever arise. And all of the parts, keys, bumpers, rubber sensor caps, felt, etc., are available to the consumer through Yamaha’s parts center, at least in the U.S., not sure about the rest of the world.
So, my take on Yamaha pianos with GHS is, that they are relatively inexpensive, they last a long time, are easily maintained, are fairly lightweight (mine is around 24 pounds), the mechanism is pretty quiet, easily modified, and are probably easy to find locally and online.
Every so often, I feel like I want to buy a “better piano”, and after listening to video reviews, reading comments from users, and trying some of those “better pianos”, I have not been able to justify the purchase. Maybe if the electronics fail, I’ll look again. Or, if something happens that I can’t fix. But, so far, it’s “the piano”, and I’m comfortable with it.