The reason for the 103hp integrated manifold/ cylinder head is to keep the turbo (manifold) cooler as it is now cooled directly by the radiator. This lets them run more boost while maintaining normal turbo temps.
This wouldn't be an issue normally, but a hot turbo can easily be cooked by the S/S since as far as I can tell, there's no S/S parameter that monitors turbo temp.
A lot of people say 85hp is a lot for 875cc, but it's less than 100hp/l and that's with forced induction. It's actually quite pitiful if you consider the 'tech' in the engine (Ford's Eco-Boost manages 123hp/l by comparison).
My theory is that there's actually a 'lot' of headroom built into the TA, my car with less than 500km on the dial, running the A/C all the way up, two people, in the hills, on a 40+ degree day has never reported a coolant temp above 88deg C. Most cars run around 98. Sure coolant is only indication of how stressed the little engine is, but I'd suggest it's 'low'.
I plan on getting a chip as well, the P-Tronic version claims 115hp without increasing boost pressure. I think that claim is optimistic, but if it does manage say 105hp without any extra burden on the turbo, I'd say that's a win.
If I did up the boost, I would switch off S/S and not worry about it, or possibly fit a turbo temp sensor that interfaces with the S/S, it might sound hard, but it could be easily wired into something like the clutch switch to simply defeat S/S when the turbo is hot.