Switch front and rear tire for distributing wear
You may have flat-spots on the rear tyre and I am not sure whether I would want that on the front. Plus you will be spending a lot longer with the tyre levers if you 'rotate' them. Valves are a bit sensitive too - mess with the tyre/tube too often and the valves can 'waggle' out of the tube. Personally I would let the back one wear out and replace it when it is 'done'.

But this all changes if you are on a long-distance tour. If you were going from Sierra Leone to Somalia, dodging lions and land-mines, then you probably would not find too many places on the way to stock up on fresh Schwalbe Marathon Plus tyres. Therefore, on the long tour, you would do well to 'rotate' the tyres (giving them a good inspect) on a regular basis.