Shimano's Dura-Ace 7900 STI levers offer a refined, asymmetric contours that offer probably the closest shape to a true anatomic/ergonomic lever on the market. Hidden shifting cables add hand positions and completely clean up the cable routing. Semi-exposed internals with uni-directional carbon shifting blades help reduce the weight 40 grams over previous Dura-Ace shifters. Shifting stroke for the rear derailleur has been reduced by 20% for quicker shifts and a built in reach adjuster allows for fine tuning the fit for riders with smaller hands.
For info on 7800-7900 compatibility, see the Shimano Dura-Ace 7900 Compatibility Chart