Showerhead design is often lacking in many products...they may look good, but perform poorly. The only federally mandated thing is that a single showerhead can't flow more than 2.5gpm. It does not address multiple, separate shower heads. Some of the low-flow heads feel like getting hit with needles. There's an art to getting good coverage, with enough flow to wash the soap off and feel good. I've not directly compared many, so can't comment on what's available. I'd be leary of one using 0.5gpm, but that's a gut feeling, not an observation from fact.