Hi Pete,
You can read off your actual coolant temperature from the bike's sensor using the built-in diagnostics - it's code D06.

How hot the coolant gets depends very much on the climate you're riding in, and to a lesser extent on how hard you're riding and the level of tune of your engine. My XTX typically only gets up to around 86deg max, even after a fairly good thrashing, but that's in the UK where we don't really get any hot weather! (Certainly not this year anyway )