I would absolutely recommend it with the only concession being to Gregg's point. Do they want to get their hands wet and go down the rabbit hole? Then absolutely. My first tank was low-to-no kh, and I knew nothing about plants or tanks--never so much as kept a bowl with rainbow gravel in it even. I never ran into any problems with 0dkh, probably because of a couple other points brought up here (regular basic maintenance and a bit of reading and research)
@plantbrain also appreciate you commenting here Tom, I honestly didn't know the ppm of injected co2 would be the same regardless of KH. That was super interesting to read, I have to sharpen up my rudimentary water chemistry knowledge somewhere along the line.
@GreggZ we have similar thoughts about CO2 setups I think, I've never ran a monitor because my ph dips too low on injection to be of any practical use. I finally upgraded my setup with a nicely built reg and the biggest thing I sprang on were two very good needle valves and some metered handles for them, think everyone knows what I'm talking about without adding a pic...now I have a point of reference on the valve handle itself so I have an arbitrary number that says *this* is where you were getting your 1.4 drop with equipment arranged the way it was, etc...instead of having to guess or rely on a bubble counter.
The flow meter sounds like it solves the exact same issue that the handles did for me, but maybe in an even more efficient way. How easy or difficult are they to incorporate into a reg you already have, are they just screwed in with their own built-in needle valve, etc? It's something I'd like to look into adding to my setup