if i were mowing slopes, and had real concern of a tip over, the roll bar and seat belt of the sub-compact would be very appealing to me. i have seen the first hand results of an x-series roll over. we repaired one @ dealership. i still to this day cannot get the thought of a person getting tangled up with a mower deck. plus you should be able to set the sub-compact up wider, by flipping the wheels around? i would also think you could ballast the sub-compact to be a little heavier.