I find indexed half-step drivetrains to be very quick and efficient. 7s is about the max that most C/V drivetrains can handle in the realm of half-step setups. A 5s half-step drivetrain could effectively be handled by a 6s indexed shifter with the appropriate FW choice. I currently have a 7s indexed half-step setup that has nearly identical shift ratios for all 14 gears. But that discussion can be found in the Half-Step thread.