the necessary change in management that an XT fork would involve,
What kind of "change in management" are you referring to here? The different set of lead developers, perhaps?
That, yes.
I'm more than a bit concerned that the big block mod, generally, will force marginal mining nodes off the network. I know that it would prevent the broadcasting of whole blocks, and likely even naked merkle tree data, over datacasting paths such as Outernet. If we are going to make changes for scalability, why are we not making naked blocks the standard broadcasting method first? That alone would reduce redundancy.
Those concerns will end up realised no matter which way the dev team go, max blocksize is increasing above 1MB no matter what. The usage examples you gave will need to take a new approach.
Another less cited new feature of the XT client is a change to chain selection/consensus rules. XT clients don't follow the longest chain, they follow the chain with the highest XT checkpoint embedded into it.