oh finally a good news, so 27 at 130w, do you have proof of the wattmeter? 27MH at 130w is very good, but apparently the nano is doing somehting like 20-22 at 80w, so it's not worse at all...
still they will be pretty expensive, so i would avoid buying right now, you can buy a 970 for cheap(230 euro, used) that does 20.5MH/140w
7950 is bad for resell, no one will buy it after you are done mining ethereum
also the consumption is higher for sure and hash lower, as you mentioned 36 for 350w(i assume the highest since you didn't provide a precise measure) is far worse than 41 at 280w
also there is not only etehruem which is profitable right now, there is at least another one which has the same profit, and amd is bad at mining it