Definitely SRAM Red, had it for a year now, and love it. The shifting is nice and crisp and it is very stiff, and also surprisingly easy to get used to
The double tap is their buzz word for their gear changes. It's all done on one leaver, basically you tap the lever to move down the cassette and then push it (i.e. a bit further, about the same as a normal DA gear change) to move up to cassette, hence the double tap. You can move up 1, 2 or 3 cogs on the cassette depending how far you push the lever, but it is all done with a satisfying click so you know when you have shifted.
Comments
Campag Record..........nuff said
Even SRAM Force is as good as Dura Ace in my opinion.