One thing to note about the DA downtube - it isn't a cutout. The front of the tube is the same as the front of the rest of the tube. So when the wheel is turned, there's no concave cross section in the wind.
Felt Bicycles invited a small group of media to its headquarters in Irvine, California. TriRig was there as they unveiled their 2013 line of tri bikes, including the brand new B2 and B12 bikes, which borrow much of the tech of the flagship DA lineup, but put them into a budget-friendly package. The B12 frameset can be had for just $1,749, which will be very attractive to those building a new bike from old parts.