I've had an interesting offer on a NOS »old style« chronomat with a blue dial, white subdials and batton indexes on a leather strap.

I hope I don't seem nitpicky, but I'll offer a little clarification. The "old style" to which you're referring is the Chronomat "Evolution" or "Evo." Because the style of the Chronomat has changed so many times, the generic description of "old style" doesn't really nail down which version you're talking about. If you call it "Evo," everybody will know exactly what you mean.

As for your question, I haven't had many firsthand observations of the blue-dial Evo, but what I've seen of it, I liked. My opinion is the blue dial with batons is sort of an iconic look for Chronomats, so it's a good one to have. The baton dial on the Evo has a bullseye pattern, alternating matt and guilloche textures. My best recollection is the blue is a little less vibrant than a royal blue, but nowhere near a navy. B-Source's owner did a video review of the blue Evo on Pilot bracelet, which gives you a better view of it "in the steel." The lighting isn't the best, but it still might help you see if it's what you like.

You're right, it was a poor choice of words and too general. I thought about calling it the "Evo", but as far as I know, it was named that for a while, and then they went back to just "Chronomat".

That's exactly right. It started as the Chronomat Evolution, then reverted back to Chronomat. Still, if you refer to it as the "Evo," or "Evolution," people will know which one you mean, since that name still refers specifically to that design, whereas "Chronomat" refers to every Chronomat design since 1984 (and technically even before that, if you include vintage designs from way back). Since the Evo has now been discontinued, it's a little tricky to know what its name is officially. I suppose technically there is no Chronomat without further qualification in production any more (see below), so maybe the Evo will officially remain the "Chronomat" postmortem.

If you really want something to wrap your brain around, the current Chronomat started out as the Chronomat B01, named after the new in-house movement inside. When the name of the movement changed to the 01, the name of the watch changed to Chronomat 01. Now, they have a 44mm size and 41mm size of the watch, so the names are now Chronomat 44 and Chronomat 41. Many people still refer to the Chronomat 44 simply as the "B01." This still works, since even though the 01 movement is in other models now (the Navitimer, Transocean, etc.), only the Chronomat featured the movement when it was named the B01. Clear as mud, no?

If you really want something to wrap your brain around, the current Chronomat started out as the Chronomat B01, named after the new in-house movement inside. When the name of the movement changed to the 01, the name of the watch changed to Chronomat 01. Now, they have a 44mm size and 41mm size of the watch, so the names are now Chronomat 44 and Chronomat 41. Many people still refer to the Chronomat 44 simply as the "B01." This still works, since even though the 01 movement is in other models now (the Navitimer, Transocean, etc.), only the Chronomat featured the movement when it was named the B01. Clear as mud, no?

@David82 Driver8, one of our two mods here, has an experience with a blue faced and blue croco strap even though I think that his was a Navi. He might want to post any pics or give his opinion on the matter. If my memory serves me well though, he got to sell it because he found it to be not that flexible as far as wear combination goes, even though he did appreciate the watch a lot.

My simple opinion is that while I don't like blue straps in general - limitations as stated previously - the watch itself looks amazing.

I also forgot to mention, I have seen a blue croc strap in person, on a Montbrillant Olympus. It is VERY blue.

My photography is a long way from good, but I feel that this is a fairly accurate colour.