The regular G10 one is pretty useless obviously. Soldered AMD CPU, cheap design etc. No iLO. It's more of a home entertainment thingy, nothing enterprise-class at all.
I agree I'm looking for something lower power too. I have three G8's but they are each doing 50W idle so I can't run them 24/7. And this is with the lowest-TDP processor that is available for them! (E3-1220Lv2, 17W TDP). The iLO alone is consuming 5W even when it's off.
I'm not sure how much power the G10 Plus draws but I haven't really considered it. It's too expensive still (I bought all my G8's for 175-200 euro each and 2 of them even had a 60 euro cashback on top of that!! So I barely paid more than 100 for them brand new. Crazy cheap pricing for a well-built 4-bay server. Each of the drives inside them cost more than the server itself :)
But 15-20W I think is very ambitious with 4 3.5" drive slots. 30W would be doable I think.