I had considered the Lightning cranks, but when you calculate the real world weight of things (930g set + 20g steel bearings + 70g timing chainrings + 20g timing chainring bolts = 1040g) the weight savings are significant but the price is really quite imposing (around $1500 before chainrings). That makes a weight difference of 200g by my calculation (maybe 300g by other estimates) at a price difference of $740. So around $3 per gram saved.

On the whole that cost per gram saved isn't too ridiculous, and saving 200+ grams is a huge deal since it is hard to shave off that much weight anywhere on a bike. But, and this is a big but, the problem for me was in having a fixed TOTAL budget. With under $3500 budgeted for the whole build in addition to the frame/fork, The Lightning set ate up around 43% of my total budget while the daVinci took only half that. If you think about it as dollar/gram then the lighting cranks are worth it, and if the budget was bigger by $500 or $1,000 I would probably have gone for that as one of the first changes, but when I tried to figure out what I could buy along with the Lightning crankset and keep my budget within the limit I had imposed, it just wasn't possible to build the bike as light as I did. All the other parts had to come down in price by an average of 20%, and that meant significantly heavier parts throughout, which outweighed (literally) the savings of the crankset.

A final consideration that came into play was also customer service. I emailed Lighting 3 times over a month long period and only got a single very terse and not very helpful reply. Todd at daVinci on the other hand went far above the call of duty with me working out all the details and I felt good about supporting them and buying what I know to be a highly reliable product. I also had a few fears about lightning's reliability as there seems to be at least a few cases of broken crank arms of the lightning sets, and almost none of the Specialized (who licensed the design from them, but seems to build them on their own). Given that there are likely far more specialized cranksets out there than lightnings, this made me guess that it is a manufacturing issue on Lightning's side (which they may have solved, I really don't know). Put that together with a number of complaints on message boards about the finish on the Lightning cranks having cosmetic issues, and I was simply worried that the cranks are simply built too light without quite enough care.

Given our current lumpy terrain (central MN), and the fact that I really like the SRAM shifters, a double was the right choice for us at this point (and the 50t is just fine on my road bike, so it should be just fine here as well).

Gates drive could be an option, but I had heard that the exact design of this frame (2007 Calfee) might have some slight issues with fitting it, and I'm just not sure the technology is quite there yet, but I'll definitely think about it when my timing chainrings get near needing replacement depending on where the tech is at that point.

Oh, and regarding the power-domes: Definitely light and interesting design, but way too expensive for the weight savings and not available in the 12-30 that I wanted.