So, I think I've figured out how to fairly easily build a flow tester of sorts.

I can use water as long as I keep the surface being flow-tested submerged - that eliminates surface tension. So, the "test rig" consists of a 2 liter bottle with a few different caps - each with a different "port" cut in it. Drill a hole in the bottom of the bottle as a vent. Plug vent hole. Fill the bottle with water. Fill a sink partially with water so the bottle cap can be submerged during the test. Screw the test cap on and cover the "port" with thumb. Turn bottle upside down, submerging the bottle only to the neck. Pull the vent plug. Uncover the port and start the stop-watch at the same time. Stop the timer when the water level reaches the neck. Keep the bottle's neck level with the water in the sink the full duration of the test.

My high school physics is a little rusty, but I think this will give me a good comparison of flow rates of different types of ports.