Several parts to this...
First, the Yamaha GHA action has the reputation of being a very faithful -- as these things go -- reproduction of an acoustic piano action. Therefore, it should be possible to get the same level of expressiveness on it as you would an a real Bluthner, for example. You do have to practice on that instrument, to get the feel for its particular touch. May I recommend that you really work on getting your playing to the point where you like it on that instrument? If for no other reason, should you ever be faced with a real acoustic grand it won't come as such a shock to you...
The reason for recording piano -- or any other music for that matter -- right through and choosing the best take, rather than picking and choosing or even recording just a section at a time is many fold. First, only by playing and recording right through will the performance be completely coherent. This applies both to the performance itself -- the way the music flows as a single whole -- and to the acoustics, particularly if you actually record in sections, rather than splicing bits of one take into another; there will -- or should be -- some reverberation or at least echo from any previous note or notes in the sound of any following notes, unless there is a very long rest, and if it's not there there is something missing in the recording.
I would emphasize that I am NOT a golden eared audiophile, but I am a practicing musician of many years. I can't always hear when a single note or two has been spliced into a recording -- although it's often audible; I can almost always hear when two takes have been spliced together end to end, even if the tempi are exactly the same (rare) and the splice is exactly right so there is neither time compression nor extension over the splice (even rarer). I realise -- all too well! -- that this is now common practice, even on the finest professional recordings (although with them, I'll give them credit -- they do try very hard to make the splices at some logical and musically reasonable point). In my humble opinion, the very finest recordings which have ever been made -- taking into consideration fidelity and timing problems, which let early recordings out of the picture) were the Mercury Living Presence series (all recorded in single takes, with one microphone for the monaural and two for the stereo series) and the London FFRR and FFSS series, done the same way. Some of these have been remastered for digital, and it is worth tracking them down to see what a difference it makes. There are a few -- a very few -- modern recordings done the same way, but one really has to look at the fine print to find them.
I would also note, however, that if the recording has been mashed into a .mp3 format and strained through an iPod, that it isn't going to make a darn bit of difference how the original was done, so... I guess I'm just old fashioned.
Topic: Recording On The Piano ???