I have been mining for 6 hours with 3 miners, rejected + stales stabilized at about 5%.I think there are some time-frames that this appears to be higher or lower, but the overall reject rate, according to cgremote is that, which I think it is fine...Could be better but it is a good start

I didnt lower intensity because I am using r9 280x at I-13 but I added --scan-time 1 and --expiry 1