Brewmoor, from what I have gathered maximizing the flow stems from the desire to whirlpool at the end of your boil. I have read here that restricting the flow can alter the results of the trub cone you get from whirlpooling.
I have not personally confirmed any of this as I am in the building stages of my system and am new to whirlpooling and immersion chillers. My old system used a chillzilla counterflow and we never whirlpooled. In the summer there were some painfully long cooling times on our 11 gallon batches, like 40-50 minutes. In my new build I am looking to avoid that.
I am planning on using the barb fittings that you have for myself, and see how my trub cone comes out. If I need more flow I will create a pair of hoses that are high flow and am curious.
Do you use your fittings with a whirlpool/recircualtion at the end of your boil? If so what pump or gal per minute are you moving the wort at? and what size kettle to you have?