I can recommend using Vision Reverse Brake Levers with Tektro 926 Mini-V front brake and Tektro RX6 rear brake. My commuter fixie uses this arrangement. There's plenty of stopping power with each brake, even with the relatively sharp brake levers. The front brake has a noodle with barrel adjuster, while the rear brake housing has an inline barrel adjuster. Another bike in my collection uses the same brakeset with Sram Doubletap levers. Braking performance is great on that bike, too. Those bikes are frequently ridden in rain; mud; and wet, salty roads. One of my wife's bikes uses the Vision brake levers with Sram road calipers -- again it works totally fine. Make sure your cables and housings are relatively clean; cable doesn't have any kinks; housing has no tight bends; and that the cable isn't rubbing on a housing stop.