I think, at least at the moment, I'm more into Arabic numerals over Roman numerals. Though I'm not apposed to owning a Roman numeral faced watch and one, or more, would/will probably find their way into my collection. For the 3520 thought, I like the Roman numerals more than the Arabic numerals. I think it has to do with the fact that the Arabic version has gold hands and numerals. It feels like there's just too much gold While the Roman version has black hands and numerals which give more contrast to the dial/bezel and match with the strap.
I also know exactly what you mean when you mentioned the National Gallery of Art in D.C. It really does relate to the 3520/5120. My brother, who is currently backpacking across Europe, loves architecture and art. So I've been fed a lot of info on the subject and seen many of his drawings. Anyway, back on topic, the Breguet, to me, is just classic/tradition. I don't feel that it's quite modern at all. This is most likely because of the typeset.
I absolutely agree that the current watches are getting larger and larger. I, like yourself, like the smaller watches. For me it's 33-36.5mm, but of course there will be a time that I find a watch that I like and it's only available in 39mm lol. &yes, they shouldn't draw attention to themselves and just work with almost anything.
Yes, that is one of the defining reasons I got the Norma before the standard Tangente. For my first serious watch, at least serious to me, I wanted to have a large amount of versatility. As far as replacement straps go, I've been using
www.thestrapsmith.com, he hand makes his straps and I've been very pleased with the quality and the price. Also, standard replacements from Nomos are quite affordable as well, at $110 per set. I'd actually really like to try throwing on the textile strap that comes on the Ahoi onto the Norma, but alas the Norma and Ahoi have different sized lugs, 18/20mm.
Haha yes, many do live quite the "charmed" life, some more charmed than others.