Is running an S9 in your garage centralizing? (Not being oppositional, I genuinely want to understand the difference).
Discussion
Not at all, man. It's a good question. Not centralizing for the network in the short-term. But if only a handful of companies (or fewer) build miners and their software, it creates a weakness. Supporting open source mining helps prevent that. So yes, for your money a used S9 will provide a better short term return. But there may be longer term impacts if everyone goes that way.
I didn't even look at the S9 power usage before responding. That's also a consideration. At the rate BitAxe is moving, I would not be surprised if you could heat your home with the miners for less than Antminer equipment with a better return within a few years.