You can, it's just you'll get a different feel in different conditions. Wet weather tends to magnify performance and if one or other is much better / worse in the wet, it can make handling a nightmare.
4x4's it's often even more important as the diffs and sensors need the same tyres so if distributes grip properly.
Side to side is a definite no no though!
I've run different tyres front and rear for 12 months with no problems whatsoever, surely with any tyres they will feel different front to rear as you are running a different contact area (tyre sizes) and the power is going through the rear
have you run different sizes and had problems, is that why you posted that ?
to the OP , given the chioce out of those tyres..........falken
That's pretty much my theory..