There's another nano watch kit on Kickstarter that's worth paying attention to, Tim McLellan's The Ultimate One - Quad Mountain. The main difference with McLellan's project is the orientation of the nano in the wristband.
Most of the nano watch kits to date orient the nano with its dock and headphone ports pointing left or right. The Ultimate One puts the nano's ports in a top/bottom configuration which adds usability according to McLellan. He points out the Nike+ and D670 bluetooth adapters can be used in The Ultimate One without affecting wrist movement.
McLellan's design idea came from user testing in this area where he found that if the connectors (i.e. Nike+ or BT) ran parallel with the arm there was a potential for interference with your movement and a higher risk of damaging the connector.