I do not use Flow Frames in the brood box, no.
Every product will have its merit for whoever buys it. @Doug1 above said why he likes black plastic foundation in wooden frames for the valid reasons he mentioned. I personally won’t touch it, but then I don’t have bears, and I’m not a commercial operator.
For me, a backyard beekeeper with a handful of hives, nothing will beat natural wax foundation and letting the bees build their own. My preference for my circumstances is natural wax comb and it has nothing to do with being a futurist or traditionalist.
I also want to point out that building up some hands on experience will go a long way to help you decide what might work, and not for your own circumstances. I say that from my own experience - I had a lot of ideas when I started out, that turned out to be not so great.