i am doing my first grow and i topped both my plants.The results seem good as there is 2 main stems with lots of bud sites ,i assume this is twice the amount than there would have been had i not..although i feel i am missing something somehow ,since they are both topped i kinda wanna know what a non topped plant would be like right now..so i would say top half yor crop and compare the results to see what you prefer.thats what i wish i had done.