G7's aren't actually that bad - when we upgraded our PFSense box from a G5 to a G7, I seem to think the power consumption ended up at something like 80 Watts.
I'd suspect the microserver would idle around 25/30 Watts. It's more the scaling based on load is where i'd see consumption ramp up.
The Microserver would probably cap out at 50-60 Watts. My DL380 G10 is generally idling and sits about 230-280 Watts - Two 12 core CPU's, 384Gb RAM, and Two 1TB drives (Storage is provided by JBODs which are separately powered). I've no idea what it would cap out at.