On 1 August 2015 at 01:17, Gregory Maxwell <gmaxwell@gmail.com> wrote:

One can quite easily transact in a way to intentionally produce such a
split to seperate the existance of your coins onto the seperate forks;
just as anyone would need to do to perform a reorg-and-respend attack
on a single blockchain.

Right. Why anyone would want to do this intentionally, however, is not clear. The coins would be worth less as they wouldn't be fungible across the chains anymore.

Additionally, new coins will be issued, along with fees, on both
chains. These new outputs become spendable after 100 blocks, and any
transaction spending them can exist exclusively on one chain.

This is something that hadn't entered my mind when I made my assertions. At the moment I can't see any way to avoid this fact.

Also any transaction whos casual history extends from one of the above
cases can exist only on one chain. This also means that someone who
has single-chain coins (via a conflict or from coinbase outputs) can
pay small amount to many users to get their wallets to consume them
and make more of the transactions single chain only-- if they wanted
the process to happen faster.

Wallets could detect this and notify the user. Due to Gresham's Law, I'll admit the observation that these outputs would likely get spent in preference (as they are less fungible), but whether the payee would be happy to accept them is a different matter.

> Miners will migrate to the bigger chain in search of higher profits due to higher volume of fees

The migration remark is a considerable oversimplification. Imagine if
I released a version of the software programmed to reassign ownership
of a million of the earliest created unmoved coins to me at block
400k, and then after that I made transaction to pay 5 coin/block in
fees. Would miners move to this chain? It pays more in fees!

Well in your example they wouldn't, because they know that your version wouldn't be accepted by the economic majority. But it's not as clear cut for the larger blocks case. They may move over gradually as they see the new chain gain acceptance, demonstrated by the higher trading volume on it.