Courtesy of Justin Fore at Fore Innovations LLC:
Most fuel pumps have a brushed DC motor. The reliability of these electric motors is subject to the wear of the brushes and commutator, which is greatly affected by the current that must be passed through these components. (more current = more arcing = more wear = less reliability) A single pump setup requires the entire electrical load of the fuel system be placed on one commutator, which is why large pump motor manufacturers require a controller to reduce the pump speed when less fuel is required. Conversely, in a multi OEM pump configuration, the current is distributed across two or three pumps. Additionally, OEM pumps have millions of hours of development and refinement behind them and are designed to run full time over their entire life. Effectively, a multi OEM pump setup is the most reliable high performance fuel pump configuration on the market.