Believe it or not, they best way to save on power with a Reeflo is to gate it down after the pump. Swapping the impeller won't really save on any energy.
As for the noise, my Dart Gold is damn near silent. I can't help but wonder if your noise is harmonic vibration/noise due to the rigid plumbing on the inlet side and the flow diverter on the pumps outlet adding additional weight to the pump which then transfers onto your hardwood floor and or through your plubing. A short length of flex PVC in the inlet side might help a bit. Also, I see you have foam under the pump but is there any rubber under the pump? I see something black under there but can't tell. Mine sits on a 3/4" rubber mat but it's also concrete slab under that. On the other hand, noise is a relatively subjective thing and given that your pumps are on a hardwood floor which will reflect some of the noise and your stand is open at the moment, you are bound to hear more noise than if your stand were closed up and floors carpeted. I also went to great lengths to sound proof my system but even with the doors open below the tank and my tile flooring the pump noise from my Hammerhead Gold and Dart Gold is negligible. Especially compared to what it was before I switched to Reeflo pumps.
Just a thought if it's not too late. You might really want to consider a pond liner below your tank to protect your floors unless you already took that into consideration. You could lay it down and attach it along the horizontal framing around the base of your tank stand. God forbid you have a leak or need to work on your pumps, the water would be contained and your flooring would be protected. I've done the same thing and it's come in handy!
That said, your tank and plumbing is looking great! Love your attention to detail! Really like your fish room setup! I wish I could have laid mine out like that but had plenty of constraints when it came to where my equipment would go.