Quote from: Zangelbert Bingledack on January 03, 2016, 12:21:30 AM

BU will let the user select a given Core or XT BIP (this is still be worked on (BUIP002, probably not supposed to link it here)), so for example if they turned on the BIP101 option, their node would mimic an XT node as far as following BIP101, including the 75% threshold and specific starting block.

Really? How? So far what I have seen is that a new block size limit in BU takes effect immediately. There is no mechanism that does the supermajority fork process.

If there is a specific option to for the supermajority fork process for a single BIP, then there should be that for every BIP. Will BU have options to allow the user to support whatever BIP or not? How will new BIPs be added? Through a software upgrade?

Quote from: Zangelbert Bingledack on January 03, 2016, 12:21:30 AM

Just like today, where if XT were winning Core miners might switch to XT, and if not they wouldn't, it's the same dynamic: if XT were winning, the BU miners would likely set their blocksize settings to BIP101. They can do this even faster than Core miners can switch to XT since it's just a GUI setting, not a new client to download.

A new client download and install takes about 2 minutes, it's not that big of a problem. Even so, the miners would have to either switch to use bigger block sizes after the fork happens or somehow indicate that they are supporting the bigger blocks before the fork (e.g. the supermajority fork process). This means that that larger block size should not take effect immediately.

Quote from: Zangelbert Bingledack on January 03, 2016, 12:21:30 AM

They can just follow Core. BU can be set up to default to Core behavior (it doesn't now, but it's an experimental release; anyone could fork it that way, trivially). I mean, you could say the same about XT: dumb users might try using XT. Could happen. This certainly isn't a security risk, or else Bitcoin is doomed because there's no way to stop people from releasing forks. Yeah I know XT has the 75% failsafe, so then imagine the reverse: everyone is using XT and someone dumb downloaded Core with its 1MB cap and tried to mine but kept not being able to build any blocks because their client rejected all the XT blocks.

Point is, the situation today is that miners and nodes need to pay attention to developments today. They can't just blindly trust whatever Core puts out - and if that's the expectation then we already have bigger problems.

Sure you can't blindly trust whatever Core puts out, same with XT, BU and every other software implementation.