> Why use a relational store? If you’re working with a system that will only be read and written by an object based language? Why keep converting back and forth between a relational model and an object oriented model?

Well I can't tell you what the right choice in your system is, but in the general case I think going with a relational model by default generally makes sense because it's rather future proof. By that I mean a relational model gives you the most flexibility in the future to evolve your system in ways you couldn't/didn't anticipate when the system was initially designed.