Rene Herse cantis work great with Campy brifters—and with all 'modern' road levers, too. I run either Campy Ergo levers on bikes with Nivex or dt shifters (shifting internals removed) or SRAM eTap (with shifting parts) on my Unbound XL bike. Rene Herse cantis don't need as much cable pull as other cantis, because there's no slack in the straddle cable.
How does this work? The straddle cable has swivelling ends, which reduces the stress on the cable. That's how we can use a smaller-diameter cable, which doesn't bow. Since the straddle cableis always taut, when you pull the lever, as soon as the pad touches the rim, you have full brake power. With 'standard' cantis that have a thicker straddle cable, the cable always bows a bit, and you need some lever travel to pull it tight before the brake pads start squeezing the rim.
As the previous poster mentioned, you can also use a canti-specific lever or classic road lever. Those pull more cable, so you can use the 'no slack' to set the pads a bit further from the rim, without the risk of running out of lever travel. I'm surprised that most other cantis clamp the straddle cable to one arm. Canti arms move a lot—the infamous 'cosine error' lamented by Jobst Brandt—and that puts a lot of stress on the cable where it exits the brake arm. That's why you need such a beefy cable, even though the straddle cable is under a lot less load than the main brake cable (since there's a cable for each side).
Long story, but the short answer is: Campy Ergo levers work great with Rene Herse cantis (but can be marginal with other cantis).
Jan Heine
Rene Herse Cycles
Seattle, WA, USA