Hi Rikki,
Yes, it is kind of soundfonts, but highly integrated, with no virtual midi cables, so you just have to press START and enjoy playing music.
I am very interested in this, and very glad you are working on it.
Just use high-quality soundfonts!

Would be a shame to have it working, but the sounds to be less than hardware equivalent.
Will you use some existing library, or go on with a new sample set?