I have a small vegetable garden, and have been looking at the small, lightweight tillers on the Internet. Does anyone have an opinion on either the Mantis tiller or its Troybilt equivalent? Each claims that their tiller is better than the other's. Are the small ones just a waste of time, or can they be usefull in a small garden? I would like to expand the garden a little this year, but I have lots of rocks and roots in the soil (which kept me from having a bigger garden in the first place). Would either of these tillers have problems with rocks and roots? Thank you for your replies!