Travelling so a chance for some thoughts. I’ve commented on these before but now having both in regular rotation it might be useful to cover some additional observations.
Hands - useful brighter lume on the 944. They look like they are mounted on shorter posting makes for a shallower dial feel and it’s really striking in the flesh. It doesn’t look as chunky deep as a three hander but deeper nonetheless.
Dial - despite the font choices, the latest Extra Thin dial with small blocks (30 across from I series on I believe) is delightful and with the dark blue dial a light catcher in bright light. The silver works in more diffuse and dimmer lighting. Thankfully both date wheels coordinate with the dial (not the case with blue or grey 944).
Movement view - I prefer the 944 balance weight in look. I also prefer the markings. The later 1240 has lost the balance cock engravings and the rotor does not indicate positions of adjustment. The Geneva stripes are better in the 1240 rolling in the light more deeply but still not as good as Vacheron Constantin.
Feel - I’ve experimented with fit and bracelet length and the articulation. The 944 is 0.4 mm thinner than the 2.62mm of the 1240 from my measurements. This is clear when you pick them up and swap between them overnight. The 944 is waif-like but the 1240 is still a lightweight just not as dainty and the only difference is that .4mm of steel. The flow on the wrist of both is equivalent perhaps even the venting of the 1240 better. However the 1240 is a different chunkier aesthetic in appearance and feel from the outer surface. The surface of the 944 bracelet is smoother, more silken. Users with a smaller wrist will probably not enjoy the single fold clasp from comfort POV but It is more discrete. I have grown to tolerate the thicker double clasp of the 1240 and it does allow a more symmetrical footing on the wrist but it seems less appropriate. The double release has changed design compared to the earlier ones due to screws loosening off in use.
Time for tables up and seat backs upright so to summarise I’m keeping both as they both have their place but as discussed before there is an ultimate watch sitting between the two.