Better to start with a needle valve, or a flow restrictor? I'm planning on using a single 100gpd membrane to start since I only have 10 taps right now. How to size the restrictor?

I found this site... http://www.purewaterproducts.com/art...ow-restrictors

But I'm sure that's for normal tap water temperatures, and not near freezing temperature sap. That will reduce the flow rate, and then how to calculate the proper restrictor? I'm liking the idea of the restrictor vs babysitting a needle valve.

Also, can you adjust the needle valve by monitoring pressures in the system somewhere, or are you always measuring flow rates instead?