Not sure about Taylor's cost differences between sapele and ovangkol. They're both great woods; it probably will depend on what you like to hear in a guitar. While I truly like sapele, I usually prefer mahogany to it. I think that ovangkol blends some of the better aspects of both mahogany and rosewood, making more of an all-purpose tonewood. As far as binding, I believe that they're both plastic (which is considered the most durable material to use for this purpose). If I had to chose, I'd normally go for a darker vs light binding, but not always. A bound fingerboard can add some elegance to a guitar's overall appearance. In the end, you'll need to pick the instrument that speaks to you best. For me, it would be a 400 series vs a 300 series, but you can't go wrong with either... hope this helps.