Whether it is nobler in the mind to buy a second edition of a book that I already have custody of the first, or to await the third, perchance to die (first).
It's a rapidly moving field. But it's an expensive book. The author projects a 2022 publication date. Actuarial tables suggest a slightly better than even chance of still being alive by then, but a significantly larger chance of being too senile to comprehend it.