Ok sorry for any confusion.
The Moteinos have a 1x6 FTDI header that plugs directly into a FTDIAdapter. So you can program it that way.
However for kits like SonarMote and MotionMote there is an integrated FTDI chip onboard those PCBs and once you plug in the Moteino on them, the Moteinos can be programmed through the USB ports of those boards. So don't solder the 1x6 header otherwise they won't fit in the case any more. So ... you don't need the FTDIAdapter when the Moteinos are attached to the SonarMote/MotionMote.
However I would add that it's still useful to have a FTDIAdapter around.