Apropos of this interesting stirring paper:
1. The paper includes an excellent warning about how degrowth is capable of being hijacked by conservatives or worse. However, this is not just Miegel, but can be seen across multiple strands of the literature, including Alain de Benoist in France (years before Miegel), Giuseppe Giaccio in Italy (strongly influenced by de Benoist) and Robert & Edward Skidelsky in the UK (favoring Christian spirituality like Miegel, but also a melange of virtue ethics and anti-Marcuse rants).   
2. Not so prominent in the paper: Democracy is an issue not only for a postgrowth society (PGS), but for how you get there from here. For example, if only rich people can get elected in your country, or if corporations are accorded human rights there, is it realistic to expect a "serene" transition to a PGS at all?
3. Is it reasonable to treat democracy monolithically, or does it mean different things in different cultures? Personally, I'm inclined to be not so relativist in my opinion of what constitutes democracy. But different cultures do have different ideas: e.g., many people inside and outside Japan believe it is a democracy, even though it's a very far cry away from, say, Germany, which by global standards has an outstanding constitution and constitutional court, and superior electoral systems.
4. A synthesis of points 2 and 3 is that there will be different political obstacles to overcome on the path to a PGS in different countries. Possibly, too, there will be different ideas of what is an acceptable level of democracy if and when a PGS were to be achieved. For example, while something called "radical ecological democracy" would almost certainly be a tough sell in Japan,  borrowing constitutional innovations from Germany might be more attractive, since Japan's civil code is already based on the Wilhelmine BGB.
5. Finally, there is a danger, exacerbated by the incursion of "governance" notions into the political sphere, but also by Rawlsian idealism, of believing democracy is some sort of efficient machine if you can just set up the rules correctly. A stimulating contrary point of view comes from the Discorsi of Machiavelli, very nicely expanded on in John P. McCormick's "Machiavellian Democracy" (Cambridge UP 2011), about how democracy comes of conflict -- especially of the rich and poor, through institutions representing their respective interests. (This is a point that might resonate even more today than a few years ago, thanks to Prof. Piketty.) Or more generally, as put by whoever wrote the back-cover blurb to Philippe Godard and Pascal Pilon's  « Les démocraties : De la Grèce antique à nos jours » (2008): "loin d'être une évidence, la démocratie représente toujours un combat."