Stretching is for tempo... I've never said they are likely to have a problem with that. But pitch shifting is another thing altogether. Two, three semitones tops without it getting REALLY weird. Remember, we're after realism, here. No point in it if it comes out even more weird than a MIDI track.
You can't derive an augmented chord from any other (amongst many others), so that's one more basic chord type they are going to have to record. And, if you are trying for better realism than current implementations (Yamaha's Mega voices are pretty good already for guitar parts), no, you can't take a recording of a C strum, and add two more notes of MIDI guitar for a C69. That would be an eight string guitar! And the wrong voicing. Totally unrealistic...!
That's the whole problem, in a nutshell. You want REAL, you have to have a recording of it. Anybody use Steinberg's Virtual Guitar? Notice how FEW chord choices you have? And not that many different styles? And it is STILL over a GB in size. And it's several years old technology.
But, don't worry... sooner or later (later, the way things have been going) the Audya will be released. And then you can have IT to be disappointed with, rather than my predictions.