I havent tried topping a solo but my latest Jack Herer solo is on the tall and lanky side. It makes her a bit unstable when the cup get light. I have been topping my bigger grows just to keep them short. I will probably top my WG solo if she hits her stride before the 18 day mark. Worse case i will just pitch the top of the stem to stiffle the upward growth but not really effect mometum.