Re: A wood that I'm not familiar with......
I have played an Ibanez Gsa with an agathis body and an Ibanez Grx with an Alder body. At first, I could hear more bass with the Agathis one, but then, the bass sounded more like a thump rather than a boom and the harmonics and jangliness can't be found whenever you play with the single-coils. The Grx, although cheaper, had the better tone and the better response to pick-up changes.
My sister has a Suzuki Sdg-10 dreadnought with a spruce top and agathis back and sides. Surprisingly, it sounded better than the Sdg-5 with basswood sides and back. If you like the way agathis sounds, buy the guitar.