I dislike Ovations, although I bought one for stage use fifteen years ago because they don't feed back (and it's been living under the bed in the spare room for thirteen years). I've got to point out, though, that Ovations are not supposed to get better - they are supposed to stay the same. The top line models have the table constructed of carbon fibre in an effort to achieve this.
The point I was making is that while the back and sides have an effect on the overall sound, the critical factor is the density of the material - a guitar with back and sides of denser wood (eg. rosewood, maple) will sound crisper and cleaner, and sustain better, in comparison to a guitar made of less dense wood (eg mahogany). The top material is the major factor in getting a better sound as the guitar ages - a cedar top will respond well immediately after the guitar is built, but will then improve very slowly, while a spruce top will improve more with age. The other factor is that instruments have to be played regularly to improve (although there are ways around this, playing them is the easy option).