molehektikpovohatSensei Raw has an older laser sensor (Avago A9500)
Zowie FK1 has a current optical sensor (Pixart PMW3310H)
Sensei's sensor has accel, FK1's hasn't!
I don't get accel with my sensei raw. I ran Mouse Movement Recorder to test it.
you can test your hardware accel like that: go into TF2, mark your mouse position with your thumb, move the mouse an arbitrary amount slowly, then move it back really fast until it hits your thumb again. If you end up in (basically) the same location, you don't have hardware acceleration