what kind of hashrate should I expect on a 270x? any recommendations for settings?
about 3x hashrate, half energy consumption, and a BIG reduction in temperature. You can use your scrypt parameters, but you can up the mem and gpu clock ( 1050 to 1200 memclock for 280x). More is probably achievable, but it's a good start and you can tweak it later.
i've found the same, when i was trying to adjust the clocks yesterday.. x11 is not that picky about exact clocks of gpu/mem (like when i was mining emc2 or auroracoin).. now, the more i'm increasing the clocks, the more hash i'm getting.. and i have a variety of GPU's (it's behaving the same on every GPU.. 6850, 7850, 2 x 6950, 7870xt, 7970)