I recently finished my new keg-based brewery and used Cam-lock fittings throughout. I bought the hose barb female fittings for my hoses, before the debate about flow rates through them surfaced.
In my mind, the answer to your question is: it depends. It depends on how often you will remove the hoses from the barbed fittings. If you will leave the hoses connected to the kettles then why bother with QDs on them? If you plan to remove the hoses after each brew session, or you change the hoses around during the brew session, then go with QDs.
I do both: move them around during a brew session, and store them after brewing so QDs make sense for me.
As a side note, I have not found the lesser flow through the barbed QDs to be an issue, for either 5 or 10 gallon brew sessions. There has been no time when the flow rate was a limiting factor to my brew operations, so I will not be bothering to modify them for higher flow.