Cecil,
You are correct that if you upsize your line you will reduce the friction loss. The limiting factor is the size of the pump itself. When I used to work there, if I recall correctly, we had a 3" Hydro-ram pump that pumped a maximum of 10,000 gpd. The way the pump works unfortunately waste up to 80% of the water in a ejection mode. Only 20% is actually pumped to your source. There may be larger systems out there, but I was only familuar with this one.
I have not worked there since 1998 so I would suggest calling them and speak with a technician to help with sizing. They may have something new by now.
rmedger-The 2'drop is required to use the kinetic energy produced by gravity. I had one customer build a small dam or berm to make the drop from his pond to the pump 5' below. From the pump to your desired discharge can be up to 10x the drop from the creek to the pump. You could use firehose to feed the water but again your flow rate would be determined by the diameter of the hose. The smaller the diameter the greater the friction loss.
