In my experience with Grados over the years, there are noticeable improvements as you move up the line and increased costs have seemed to me to be reasonably matched with commensurate sound improvement. The wood bodies are overall better than the plastic body models. The first of the wood bodies that gets my attention has been the Sonata. The last Grado I used was the 1.5mv output wood bodied Reference (about $1200 at the time, about six years ago) and I felt I'd received good value for my money in the upgrade process.
