No science here, just a one grow observation; I had six different strains going, topped 3 (which has been what I've done for years) and LST'd the other three (bent them at a young age). The combined three LST'd final weights averaged was almost 50% more than the combined average of the topped ones. Completely surprised me, but within this somewhat random group it was fairly consistent.
It might seem obvious which method I would do moving forward based on this experience, but I'm actually a bit on the fence. I find topping easier, and I strongly prefer the shape of the plant for maintenance/leaf management/trimming when they have been topped. That said, the final weight difference is significant.
Side note, if you are choosing a method with the priority being to keep them short, the three LST'd ones all had to be put up on a platform to make my canopy even, they were all consistently shorter than the topped ones.
Lastly, I was surprised that the LST'd primary colas were not that much bigger than the other main colas. Makes me think that when the primary cola gets really big and dense in an untrained plant, it's as much because of proximity to the light as it is a genetic structural predisposition.
It's challenging to get pictures that illustrate what I'm talking about, but these are from the end of week 7 after the second schwazz trimming. Front row is topped, raised back row is LST'd (ignore the one gallon plastic pot...).

One more note... This was my first time schwazzing, and the final weight of the six plants was 25% less than the previous grow, where I did almost no trimming at all and a two-stage harvest -- point being I think schwazzing can have a stress impact. I have no idea if there is any overlap or connection between the on-topic training methods -- for instance, if the combination of schwazzing and topping is too much shock and diminishes final weight while topping without schwazzing might not...