I have the S2 Mk2 and an iPad Mini too. Most of the time, I end up using the iPad instead of Traktor on my PC.
Manual beat matching is totally doable on the S2 and iPad. The only catch is, you can only nudge tempo with keylock and sync turned off.
You can use 3 effects simultaneously on each deck instead of just one at a time.
The only buttons and knobs that have no functionality on the iPad app is the remix deck control section.
My iPad sits on a stand behind and above the S2. I find that works best for me vs having the iPad off to the side.