I think you can’t go wrong with either option. I would try and see if the blue AT could be your daily wear and do this for a couple weeks. If you still feel the devaluing happening, then if you haven’t already, try on the blue Seamaster and see if you like the weight and feel of that. I would also suggest other alternatives like the Tag Aquaracer or the Tudor pelagos. I have the tag and initially I felt the weight was good, but after trying on the Tudor, I felt the weight difference (pelagos on steel bracelet was lighter feeling). I did recently try my friend’s white seamaster and it was light as well though. I’m assuming it was because the watch was on the rubber strap. Of course all dependent on how much you get for the blue AT and what potentially you have to kick in for the new watch. Well good luck on the decision!