Roger,
I have only second hand experience with R4's and first hand experience with R1's. The choice is yours to make. The R1's will give you much better performance in soft, muddy, or snowy ground because there is more space between the lugs so they don't fill up. The side walls and the tread on the R1's are not a heavy as the R4's, but if you are careful in the woods there should not be a problem.
Make a list of the tasks you will use the tractor for starting with the most frequent and next to each task put the tire that would be best suited for that task. That should determine what tire you will give you the best service.
I like my R1's for the snow and soft ground, wet or dry. I do not use the tractor for mowing the lawn. I do not have any problems tearing up the ground using it to mow a field.
Randy