Low flow toilets

Someone told me that low flow toilets should not be used if the house is on a well and septic system. Comment was that septic requires full flow (flush) to ensure that waste gets into septic tank. Is this a valid statement?

No, that's not a true statement.

Most septic tanks are right near the house, maybe as close as three feet away.
My home has a sewer link that is over 250 feet long to the city connection.
If my low-flow will travel 250 feet, then I'm sure your's will go 3 feet.