[Hmm... Not sure I agree with this. With most guitars I find that with increasing price you get better playability, sound and overall "feel", it's just that you have the law of diminishing returns - at the really expensive end of the spectrum you're paying a lot for a small increase in quality.
Cheaper acoustics improve over time too. I had a Seagull SM6 (about £350) that just got better and better. I think anything with a solid spruce top will mature.
Hence the word 'often' :) Iv'e never owned a worthwhile acoustic but I have played a few. More expensive the better it plays (usually). Same as processor speeds, playing 50% extra for a 5% speed increase.
These days cheaper acoustics can be called good (I'm old bitter and twisted). I think there has been more progress in the construction of acoustics over the last 20 years than there has in electrics. Happily this progress can be used for the more wallet friendly market. Not so long ago you had to pay a lot for a non laminate top (that wasn't overly thick)
Joe,
I bow to your superior knowledge of what happens to the wood over time. I remember laughing (in the 80s) at the theory that the electro magnet currents generated by vibrating strings modified the structure of the spruce tops (I will try looking for that magazine article). It just facinates that a piece of thin spruce has the right charictaristics when a larger piece is just so far wrong.
As for a spruce solidbody I don't think you would like to try it at all, or fot that matter MDF, blockboard, chipboard or potato ;)
Rob...