A real 4WD system (like on 4X4 pickup trucks and Jeeps) with a lockable rear axle will be just as good as the Subarus. I suspect that the rear differential gets locked only when you use 4X4 L mode though... not sure that the rear axle gets locked when shifting from 2WD to 4X4 mode at freeway speeds.
The biggest problem with 4x4 trucks is not the 4wd system or the tires but lack of weight on the rear axle. An empty bed is so light that the rear end can break loose super easily. If you have a pickup you need something in the bed to weigh it down. I used to load my Nissan 4x4 with about half a dozen bags of tube sand just to make it driveable on packed snow and ice.