Just a quick update (on the substance of the conversation, anyway) - the restore did not finish overnight. After experimenting with dozens of repeated restores this morning, I found that the data transfer tool is unable to sync the text messages. The background process stops at random points but the tool does not clearly indicate this, instead looking like it continues to sync. When I uncheck text messages, the sync process reports finishing correctly, but it still omits hundreds of items. Mostly photos and videos, but some random calendar appointments and contacts too.
While all of these are transferable by other means, it requires carefully resolving any conflicts. This is definitely not in line with the "Google, why does my phone..." advertising push, which for me is a deal-breaker issue. Of course, your opinion on this may be completely different, and that's perfectly fine. I returned the phoneabout an hour ago desipte the overall positive impression it left - the hardware is spectacularly good, and many tiny nuances of day-to-day interactions had a lot of though go into them.