I've flown as SLF a lot on QantasLink's Dash 8 fleet. In my experience, the 400 rides more smoothly in the air and through turbulence than the 300 and 200, which seem to get tossed around a bit more, being so much lighter.
On my flights with QF, the approaches seem pretty stable, but the landings always seem harder than on the smaller series (save YLHI where they slam it onto the deck!), I've had a few fairly exciting ones.