Hi PatzerNoster - thank you, thank you. Yes, stamina is exactly the right word. 464 pages over 4 years doesn't sound that bad, but it was a ton of work, thousands of hours, and many late nights up analyzing, writing, and playing training games and such. Hopefully it was worth it and the readers like the book!
I do think Black has reasonable winning chances in the 6.N1c3 main line with 10.g3. All things considered, by move 16 the players have only traded off two minors pieces, and play is quite imbalanced. The positions are definitely more clarified and straightforward than things like the Yugoslav Attack or the Bg5 Najdorf, but they're not totally dry. From memory, Almasi has lost more than once in this variation as White, once to Ivanchuk and once to Moiseenko, who has a really, really good score from this position as Black. Federov has some nice wins, Ikonnikov surely has a few, and I know Jan Markos has a couple as well. And these aren't just 2200 players, they are 2500-2700 players winning as Black. It's still chess, and the opening can only take you so far.
Like you said, the variation is playable for Black, and it all comes down to your philosophy - if you really think you need to play ultra sharply as Black in order to win, you might want to investigate the older 7...b5, or even something like 10.g3 h5, which I only mention in passing. I could have covered them, but I was less sure about these as equalizing tries (and that was my first priority), and I didn't want chapter 1 to balloon up to 75 pages or something. Perhaps if there's interest I can do a PGN update with my thoughts on these lines.
If you decide to buy the book (I hope you do!), let me know what you think, and happy hunting!
You're capable of finding these games yourself, but here are some black wins at the top level after 10.g3:
It's likely that your games in this variation won't be short, which can be viewed as good or bad depending on how you look at it!