I've seen quite a few people throwing this Theymos quote around, so let's actually take a closer look at it:
I'm impressed at the level of Bitcoin knowledge of bitcointalk.org users compared to /r/Bitcoin users.
Most of the people in this thread and other similar threads are interpreting the issues correctly (or at least with some evidence of actual thought), unlike most Redditors.
I don't think it makes sense to call Bitcoin XT an alt-coin anymore than it does the current version of Bitcoin Core, which has hard-forked several times since it was introduced. Furthermore, Bitcoin Core will only fork away from Bitcoin XT when XT has 75% of the hash power behind it.
Bitcoin's hardforks (though some people don't classify them as hardforks) were done with consensus among the the Bitcoin community/economy/experts. In the current state of the debate, any max block size increase won't have consensus, though I think that consensus on a compromise proposal might be achievable in 6-18 months.
Activating a hardfork based on what miners do is really bad. You could easily have a situation where 75% of miners support XT but none of the big Bitcoin exchanges or businesses do. Then miners would start mining coins that they couldn't spend anywhere useful, and SPV users would find that they can't transact with the businesses they want to deal with. The currency would be split, and in this case XT would be in a far weaker position than Bitcoin. The
possibility of this sort of network/currency split is what makes XT not a "legitimate hardfork", but rather the programmed creation of an altcoin. A consensus hardfork can only go forward once it has been determined that it's nearly impossible for the Bitcoin economy to split in any significant way. Not
every Bitcoin user on Earth has to agree, but enough that there won't be a noticeable split.
Bitcoin is not ruled by miners. In a hardfork, miners barely matter at all. (Softforks are different.) What's important is what the
economy does.
To summarise, he's basically saying if the economy doesn't follow the miners, there's a problem. Which is a negative spin.
But at the same time, the statement would be equally true if he had phrased it to say that if the economy does follow the miners, there isn't a problem. Positive spin.
A subtle change in emphasis makes all the difference. The only thing he's really giving here is an opinion. He thinks a fork would be bad and he's trying to make it sound as scary as possible. He's more than welcome to his opinion, but it's not beyond repute.
If Bitcoin forks and people go with the flow, everything keeps working normally. There is no drama. First we'll see if the network reaches the consensus threshold and if that happens, we'll then see who tries to fight the current and gets swept away.
That's how it would work regardless of what the client is called or who coded it. If it was bitcoin core that introduced the 8mb patch, the fork would occur once the network reaches the consensus threshold and if that happens, we'll then see who tries to fight the current and gets swept away. Same story, different name. At the end of the day, it makes no difference. Another equally valid outcome is that the alternative client reaches consensus and the core devs concede and release a version of core supporting 8mb blocks and then there's no bickering over a silly name or the personalities involved.
It's only an altcoin if it forks without consensus. If he wants to keep moving threads to altcoins because of his opinion, I honestly couldn't care less. It's only going to polarise the discussion, encourage controversy and make people dig their heels in. If anything, it's generating more support for the alternative client than there otherwise would be.
Finally a responds from a Staff member, and then it is a meme? 
is BitcoinXT and Bitcoin one and the same?
