I'm half way through an unintentional comparison of topping vs. not. The light fell on one of my Blueberry clones late in veg and I had to top it several nodes down because the light fell hard and snapped the main stalk.
Long story short... I'm 4 weeks into flowering with identical Blueberry plants except one has been accidentally topped and the other hasn't. The topped one has what looks like 4 colas forming while the untopped one has the regular xmas tree shape with a single main cola.
Harvest time will tell whether or not I start topping my plants or not.
Not much help to you, but several members swear by it. Each to their own, I guess.