We present a comparison between experiment and simulation of a 40-Gb/s periodically stationary dispersion-managed soliton (DMS) system in a recirculating loop. We find that we can propagate an error-free signal over 6400 km at 40 Gb/s and over 12 000 km if we lower the data rate to 10 Gb/s, keeping all other parameters constant. A careful analysis of the limiting factors shows the strong influence of nonlinear optical pulse-to-pulse interactions, causing a large increase in timing jitter. At a transmission distance of 6400 km, a large fraction of the jitter is due to pulse-to-pulse interactions. Moreover, we find that the system performance is very sensitive to parameter variations. We conclude that periodically stationary DMS systems suffer from numerous problems when increasing the data rate, suggesting that it may be impractical for wavelength-division multiplex transmission at 40 Gb/s.