So if I bought the ebook where does that put me on the Lego AFOL scale?
But more seriously, there are valid reasons to prefer a digital to a physical copy (for me it's accessibility - I always have a pdf-capable device with me so when I'm on the road I can easily grab a few minutes to read some more). However, if the choice is print-only or no book at all, I'll accept that in order to see the next book produced. I'm not naive enough to think that the piracy would disappear with a physical copy, but the lack of a digital copy to start with should discourage all but the most ardent "sceners". Yes, it does make me less likely to buy the book at all but at least I still have the opportunity to purchase it.
Thanks for thinking about us (I seem to be the only ebooker in this thread!), but ultimately I would suggest that you go with the numbers. I expected the print copy to outsell the ebook but not by that much. What's the split in digital sales from the Humble Bundle and through other online stores? Honestly it sounds like the exposure from the Humble Bundle has done more harm than good, I realize it's not easy to find out but do you have any idea of how prevalent the piracy was before and after the bundle went live? Did NoStarch have any previous business with the Hubmle Bundle or similar outlets, because if they did I would expect them to have given you good warning about exactly this situation - I know this isn't the first book-only bundle they have sold.
Also I seem to remember you mentioning anti-piracy measures before releasing Incredible Lego Technic. If I'm right, what came of that?
I remember hearing that big-name artists got less than £1 from every CD they sold back when single-disc albums cost £12-15, so if you factor in economies of scale and the size of the market 1/16 of the revenue sounds about right to me. Think of it as a measure of just how much work (and money) goes into making and distributing a high-quality product for a niche audience.