Topping produce 2 tops. FIM produce more.
I like to top my plants early if I decide to to get a "twin palm" kind of growth.
If I need to, I top again.
I don't have anything to do with 9-15 tops I would get for topping twice using the FIM method.
When I use a SCROG I rather top twice and supercrop as it gives me more place for adjustments.
When running a SOG kind of grow (with low amount of plants, never used more than 20 per square meter) I top twice to fill the room and LST when needed.
If I was to run a low number of plants (1-3) in a SCROG you might be better.