True, this bike is pretty light, it's not for everyone. It's a bike like all my others, custom made for a specific purpose. This one happens to be typical midwestern singletrack, which is smooth and does not involve huge bomber decents.
Most of the weight savings on this frame are actually in the components, specifically the wheels. The Notubes rims and tires are really, really light, probably too light for most, but fine for smooth lightweight riders. The Stan's 29'er rims weighed in at 404g each and the tires were about 420 g each. not using tubes is another 120g per tire, so using these wheels took about 2lbs off the bike compared to wheels I'd usually spec on more general duty stuff.
If someone who was in the 200 lb range wanted a bike like this I'd build it differently and it would certainly weigh more, probably in the 21-22lb range.
I may be building a more "production" style 29'er frame in the near future for sale in several local retail shops, those will certainly be slightly heavier frames, but similar styling and absolutely lugged.
if you have more specific questions, feel free to email me directly, there's a link on my website. Thanks for the comments