Summary of what's happened:
First comment was out of the box impression because of the 1440's brighter, more upfront and faster sound (the last point is definitely a good thing).
Second was after an hour of listening and third comment after 10 hours of burn-in.
Now, these have been fried for 24+ hours and I think the 1840 are the more balanced of the two, and more deserving of the flagship title. They soundstage and image better than the 1440 as well. I do feel the 1440 has the advantage when it comes to speed/transient response, but they're a bit hot up top and definitely less forgiving. Good thing is the treble is clean and detailed. Its peak doesn't seem as narrow as the T1's, but it's also less warm.
I can see how some would prefer the 1440 more in short sessions, such as at a meet or store. They remind me very much of a slightly refined, open 940 with a little less bass. For me though, the 1840 is still the best in the Shure lineup.
It has only been a day really so my thoughts may change a bit. We'll see...