I don't top my plants because it seems like my main strain really messed with the yield, I may try it on my secondary strain but topping really gave me smaller colas, not multiple main colas. Just an example or strains making the difference, because I know some people that greatly increase their yield by topping.
I've recently gotten into LST and have been doing it to my new mother plant, plan on making her a massive bush. Never tried SCROG though, seems like a lot of work to me, I'm pretty lazy. It's pretty interesting when you first start getting into LST because you're thinking that you could hurt your plant but in reality they are MUCH stronger than we think. I've probably got my plant tied down in about 8 places at the moment and got some new branches coming up that'll need it soon. My battle is whether to top the main stem or just leave it alone. Space is not an issue but I know that topping will increase the number of cuttings in the long run.