From what I understand (I'm at about the same stage you are), the amount of space per plant will dictate whether you need to top or FIM. If each plant has plenty of space (like 9 sq. ft. per) there shouldn't be a problem topping or FIM. It would send hormones down the plant and tell it to grow more out than up. If the plants are packed together, there's only so much available space for each bud to have good light, in which case you might not want to create more bud sites.
I'm having to make this decision myself now, and I'm growing with only 1 sq. ft per plant. So I'm choosing not to top and am trimming the bottom 1/3 of all foliage. This should give the bud sites enough space to get direct light. If I find I have more than enough space for the buds, next time I might try FIM and see what happens.