Wattage means weight. Adding more plants doesn't mean more weight. It doesn't matter if you fill the tent with x10 plants or x2 big plants. If you fill your lighting foot print correctly it won't matter which method you go. It's personal preference from there.
Go with 4 plants and try Topping/FIM. You need to learn to top/FIM before SCROG imo. Not too many plants to change, 1 or 2 could die and you would still pull off some kind of harvest. Not everything is auto-pilot with growing.