A roller pump is a "positive displacement" pump. The cut and paste is from Wikipedia:
"A positive displacement pump must not be operated against a closed valve on the discharge side of the pump, because it has no shut-off head like centrifugal pumps. A positive displacement pump operating against a closed discharge valve will continue to produce flow and the pressure in the discharge line will increase, until the line bursts or the pump is severely damaged, or both."
You'd need a relief valve if going the drip irrigation route.
I use one with a tote tank to flood the furrows at our market patch. Usually just run the pump a little over idle to get a nice flow going, that doesn't carve out the furrows. I pump from the high side of the garden, it runs slowly down to the end of the rows. If it starts running off, I move the hose to the next row. The furrows alongside the row were created by my disc hiller. Mark