I have new record for SUMO and RX550 4GB - 390H/s suprise me this small beast ...
I'm getting 460 h/s with each of my R9 380 4 GB (XMR-Stak).
Everything working stable and earning x2.2 more than before.

thats great, but i think that i burn much lower energy, than your R9 ... but its great result ...