SX sounds like what razer exactmat was before.
so its a decent pad, but shit for RM199, i rather look for other options.

what razer mouse are u using?
i also guess u must be playing at a very high sens.

i used to use copperhead, never had issue with cursor moving...but i always used a proper mousepad.

high dpi, any small vibration can see cursor moving.
like maybe from ur subwoofer on table etc.

also copperhead sensor likes to attract dust, go get a blower and clean the sensor also.