I don't see why this is so difficult. If someone is asking about running Stage 2 over Stage 1 without the supporting mods, then that means they have an AP3. If they have the AP3 then they have data-logging capabilities. If they have data-logging capabilities then they have the ability to analyze data that is applicable to them, their car, and their environment. Nobody wants the liability of saying 'yeah, run any map you want on a stock car-it's perfectly ok' and Cobb didn't design the maps to be used that way.
If you run a map that is designed on supporting modifications that you don't have, you're taking a risk-it's that simple. Someone that only goes WOT occasionally on their daily drive is taking less risk than someone that takes it to the track, so your choice should be dependent on just how risk-averse you are/aren't. Collect the data in situations that are applicable to you, analyze it, then make your own decision.
It's pretty much fact that the OEM IC is crap for any extended-use of WOT. IC temps are also directly linked to coolant temps. This relationship means that the more heat you introduce to the system (through the use of a more aggressive map) that the IC/radiator can't shed, the sooner you run the risk of over-heating your engine. Will it happen? Maybe and maybe not, dependent on your overall situation. Can it happen? Absolutely.
Don't expect others to tell you that it's ok when you have all of the tools at your disposal to find the answer that is directly applicable to you, your car, your environment, and your driving needs.