Counter rotating tillers break up the soil with less number of passes and do a superb job. However!!! If you have rocks in the ground I would advise against it. The tines might (will) pick up the rocks and bang them against the top cover of the tiller and get wedged in there. My walk-behind tiller has a forward and counter rotating option. I tried the counter rotating option and broke a shear pin every 20-30 ft of tilling. With forward rotation I might break one pin per season. So. guess which one I use all the time. My garden is full of rocks even after years of picking them after tilling.