I use House & garden a lot, mostly aqua flakes base. Its supposedly designed to have more minerals and micro-nutrients that would normally fall out from a magnetic pump in a recirculating system.
I use it to veg plants in coco sometimes, (mostly dwc though) and they grow real nice. Coco is hydro after all.. I also think I heard the Coco A&B has less K, but not sure? May just be a marketing scheme.
As far as using coco spec nutes, I could see doing it if you were running DTW, and it was much cheaper because of that fact. Either way it will probably work fine.
If all I had was H&G cocos a & b.. i would just treat it like aqua flakes in my recirc\dwc systems. Until I could get my hands on some more aqua flakes that is. Its so stable, and predictable.
Just now noticed they make a Hydros a/b as well.. hmmm
Anyways here is the feeding schedules for the 3 H&G hydroponic bases.. they all look the same to me, when toggling around with the settings. https://www.house-garden.us/nutrient-calculator/