Of course the Douro has much more sunshine than Bordeaux, and grapes can often attain high sugar levels, which translate into high alcohol levels in the wine. With Port, this is not so much of a problem: if you are going to fortify the wine during fermentation, it is not much of an issue whether the potential alcohol of harvested grapes is 14 or 15 degrees. With red wine the situation is clearly different, and we have certainly produced wines of 14.5 and sometimes a little higher.
Again, I think that the most important thing is how the wine tastes: if you notice the alcohol level when you taste the wine, then that is undesirable. But usually, if you have a powerful spicy aromatic Douro red, with great fruit and all its elements in balance, my experience is that you do not notice the alcohol when tasting the wine, at least not as a negative element.......
Recently went to an old Chateauneuf-du-Pape tasting. Another warm area and Grenache really needs the heat. Alcohol levels routinely 15+% even 20-30-40 years ago. None of the wines tasted hot.
