  We investigate C+L+S long-haul systems using a closed-form GN/EGN
non-linearity model. We perform accurate launch power and Raman pump
optimization. We show a potential 4x throughput increase over legacy C-band
systems in 1000 km links, using moderate S-only Raman amplification. We
simultaneously achieve extra-flat GSNR, within +/-0.5 dB across the whole C+L+S
spectrum.
