I have an 1800, been using it as a sump return for 14 months now, no problems and I have even inadvertantly run it dry.
As per the pump differences, the 1300 is a higher head pump. The 360 is 152 GPH @ 0 feet, and will pump up to 3 feet max head. The 1300 on the other hand does 370 GPH @ 0 feet, with a max head of 6 feet. There are curves for these pumps out there to show GPH at various head heights, and I believe it is either premium aquatics or marine depot that have them online.
Ben