The all-solid woods ones (not the G series; I think these have laminate back and sides) seem to get better and better with age. I've got a 26 year old EN20 that I haven't played for a long while, so I'm reasonably objective about it. Through reading this thread, I decided to take it out and have a play. (I should explain, I'd played a couple of new ones in the shop last week while shopping for a guitar for a friend). The old guitar has darkened with age (cedar top, mahogany back and sides), and the binding has gone a dark ivory colour. It has some honourable scars, but it's structurally excellent. After a few minutes playing and a slight truss rod adjustment, the guitar seemed to come alive. The tone (in my memory) was always pretty good, but this was special; huge bass, with clear and rich mids and tops. The volume was extraordinary too; much louder than any of my other guitars, including the gigantic Rob Armstrong doubleneck. It's staying out of the case for a while! IMHO, look for an older one; I played a 10-year old EN40C this week, and that was very, very good too.
Tim