Why only one is interested in higher hashrates with Claymore's miner? And personally the author hasn't interested in this case?
The miner is realy sends more shares to pool, even for both coin - ETH & SIA, and pools accepted it. There were no HW errors. Clocks are the same.

R9 270 - 15-16 MH/s
7950/7970 about 22 MH/s