Flow-control faucets came into being as a solution to the 'too short line length' problem that came about with servers expanding what they serve to include brews with higher carbonation levels than were anticipated when their systems were first assembled.
You mention purchasing 6 of them..if 6 and no more is the number of taps you need; Are they all lacking the correct length and diameter beer line? Do you have and use secondary regulators to maintain the carb level appropriate to each beer? Would simply switching to the 3mm ID EVAbarrier or longer line be a more practical solution?
When I outfitted my first kegerator, I had as a precaution, used 10' of Bevlex 200 and bought a Nukatap FC... and it is a really nice looking tap....I have yet to use or need it. My current kegerator has long enough lines to handle the highest carbonation I have any taste for, but the Nukatap FC is in my cupboard 'just in case'. The only plan I have now for someday having something more highly carbonated is to switch my 4mm ID lines for the 3mm ones.
One or two FC faucets on a keezer strikes me as practical, but a full set rather than a properly balanced and prepared system just seems wasteful.
Not denigrating at all; just looking for clarification and trying to save you some cash that could be more effectively spent before the beer reaches the tap.