I haven’t read The Time of Our Singing yet, but it sounds like I should.
As for the corporate history in Gain: well, I enjoyed it, but it struck me as extremely oversimplified. By necessity, no doubt, but I always get uncomfortable with those bird’s-eye-view, skipping-decades-at-a-time narratives, and I was put off by sentences like “and then it was time for a public stock offering.” Maybe I’m just a big nerd, but I wanted to know the individual steps that the growth of a business comprises. That said, though, I agree that it’s well put together, and it really is a reminder that the huge corporations we think of as faceless and bureaucratic used to be small personal businesses.
And there’s something about the contrast between the century-plus corporate story and the short months of the protagonist’s life/death we get to see. A good novel makes you contemplate something beyond its nominal subject, and I think Gain does that very well.