To follow that up: 45W isn’t that bad. Depending on where you live, I’d say it’s worth it if you get something out of it. (Be able to fit the HDDs, upgradability, …)

Ultimately you’d need to do the maths. Check what it costs to afford an additional 20W of power in a year and whether you should spend that money on better hardware. If my maths is right, 20W for a year at a high price of 30ct/kWh is about $52. So there isn’t that much to be gained. And your electricity might be considerably cheaper anyways.