I trust the math
I'm just saying that I have read many reliable posts that give the advantage of a known ace at over 50%. Yes, this would blend to a very high advantage over 6 hands, and in your example, the 48.5% total advantage sounds right. If I'm not mistaken, this would be an average advantage of a little over 8% per hand, so we would use that number to size bets, and also factor in the greatly increased variance. You can probably find more in-depth info on BJMath.com if you do some poking around.
I have not read this book, but I plan on doing so. The math regarding a known ace for a first card is not new, and there are a number of published methods for gaining this knowledge.
To Mr Lee - I would hit vs splitting aces if I was at an index that tells me this is the correct play. I am not aware of any such index, which means that I always split aces.