well the 3 is closer to the ground....
and of course more passengers = more weight to move around
if it doesn't stay in the lane, that's the tires slowly skidding from the intended path. just slow down to avoid deviation
i also went from a 3 to the X. the X feels like a boat when turning. air suspension is never going to be as solid as regular springs/shocks/struts.
it's going to come down to suspension height, tires, and terrain. put it on low (or very low if you know the road is flat) and you will get better handling.