Re: Why not treat BU as Alt?

No one who really supports BU would support that, as we obviously want the legacy blockchain and everything that comes with it, including an undiluted asset. We want Bitcoin to scale , not an alt.

But let's assume that the Unlimited alt works great and people find it more useful than Core. Over time more and more people move across and it usurps Core. [...]
In that scenario it started off with a snapshot of the original chain and eventually it squirts past it out of pure merit and in circumstances with no baggage whatsoever.

I could agree with that. You might even say that it would be even more respected and 'cleaner' since it would have none of the tainted history of Bitcoin (mt gox, etc).

There is one more advantage: You would have a very small blockchain at the beginning. Bitcoin "beginners" wouldn't have to download 107 GB and that would be a competitive advantage.

But the reason why I would like to see a "BU altcoin" is that it would be a way to test it thoroughly "in the wild". As many Core supporters (including me) have doubts that its consensus will work as expected, it would be the opportunity to the BU team to show that it works well. In this case it's even possible that at the end Core adopts it and the "original BTC" would come with BU rules.