Topping is a terrific way to increase yeild. Cut the new growth off, right abouve the nodes and instead of having one bud site...you have 2.
This also helps keep a even canopy so you can consintrate your light to the plant (improving yeild).

I would look at it this way. How much bud do you smoke? If you amoke a lot then I suggest growing bud..but if your an once in awhile smoker than thats up to you. Just way the risks man..before you end up spending Gs.