Should i LST or Top my Wedding cake auto ?

lst is probably better, but if you only remove a small bit of plant material when topping, that 1.5-2.5 growth nodes you clip off won't matter much in the long run. Since your auto is on it's own timer, anything you lop off can't be mitigated with a longer vegetative phase as you can with photoperiods. losing a couple nodes won't add up to much of a loss. Lop off something substantial to do it to too many branches and that will definitely impact yield in a noticeable way. Maybe, just the apical meristem and stick to manipulating apical dominance after that and it'd be fine.