I'd pass.

The only thing I use barends for are to trim a front derailleur (I hate indexed front shifting) and to adjust a rear drag Arai brake on the tandem.

Instead of barends, I'd look at getting some Kelly Take Offs and mounting indexing downtube shifters right by your levers. They work with ANY downtube shifter, and allow you to shift without moving your hands. Like a lot of things at Rivendell, the hype and marketing rhetoric doesn't add up when actually riding the bike.