The serifs are there on the Carrera, it's just that they have become pretty vestigial at this point. You hit the right nerve with modernism I think Dan - a trend away from exaggerated serifs to a plainer typography to convey progress and a more "modern" image is something we see quite often in design. Take a look at the evolution of BMW's "propeller" logo below for example:

Interestingly, some companies take the opposite tack - Sony, despite being a manufacturer of electronics etc, has kept the serifs in its logo pretty much intact. Maybe the intention here is to show that even for a modern company, it has some history:

We see Heuer go through a lot of subtle variations in the logo (obviously shallow shield to deep shield, but also in how pronounced the serifs are) and it does vary from watch model to watch model, never being quite as clear-cut chronologically as BMW's logo above. I'm in total agreement with Jeff here, the consistency from one dial to the next is certainly variable - Jeff and I had a discussion over what the S stood for in model designations when we were working on the Carrera table, given that some 2447 dials are quite clearly silver and others are a flatter, matter almost white colour. I'd wager it comes down to relying on your suppliers in the end, but I'm surprised by the leeway the dial suppliers seem to have had in terms of reproducible fidelity - I can't imagine BMW putting up with the supplier of its enamelled badges having the degree of variability we see in watch dials, for example.

But it's not so much the difference between the Carrera and Montreal dials that caught my eye initially, as some of the internal consistency within the Montreal dial itself.

Let's look at those two Es. I quite like the balance of the elements in it too, rather than the top heavy Es of the majority of models, but the execution's a bit off. The top and bottom parts of the E (i.e. above and below the horizontal bar) aren't the same width in either case, and the bottom part of the second E is noticeably curved. I've probably spent too long looking in detail at watch dials by now and should give the loupes a rest! Probably all of the dials have a few little inconsistencies like that, it's just that these black Montreals seem to have more than most per watch and it was immediately clear to me thanks to Jeff's nice clear photos of it. The execution of the shield on the blue example does seem much better.