I can't say its the best idea either. I can tell you that on the 1 plant I did it to, the new growth was the most vigorous of the 8 plants I have topped. Could it just be a vigorous grower....sure could. But it didn't hurt it so it warrants a bit further looking into in my eyes. You know me, I like experimenting with the ladies!
MY view on topping and transplanting is that as we get better at transplant there's little to no stress from transplanting.
Just don't break the main tap root. That wouldn't be helpful.
These were all root bound in solo cups last weekend. I scored the outside roots and up-canned them into 1 gallon cloth pots with no additional mykos, just plain ProMix HP. Then I topped them, taking off about 6 to 8" from each.
They are all doing rather well!