SmartFlash is about 3x the power of an SB900, say a stop or two, but at mid-range settings it should give you plenty of light and recycle way faster. The modelling lamp could replace the LED as a working light for posing etc, though one thing about the SmartFlash is it has an irritating 'feature' where the modelling lamp switches off while the unit is recycling/recharging. It's supposed to be helpful, and it's only off for a very short time at lower power settings, but I really don't appreciate that kind of help and find it distracting for portrait sessions. I don't know if you can disable it on the newer SmartFlash-3, or if it might be an issue for your application.
Re warranty, this is a contentious topic ATM. What does the warranty actually mean in practise if you need something fixed, either in or out of warranty? Lencarta has a workshop on site with trained technicians and spares. AFAIK, nobody else has that in the UK for Godox, or any other Chinese brand for that matter. It's a major consideration, not that studio flash equipment is unreliable (it's usually very dependable) but if a stand topples over (very common outdoors) or you smash something against a door while lugging it around, then sending the thing off to China for an undisclosed period, at possible substantial cost, is not an appealing option for me.