Hi
I've always been struck by the Ultra thin, especially the 34. I think that is mainly due to a tear down of one that I read - I know the W Odets one is still up on TZ from eons ago, but I'm also sure there was one here - when the site used to do full blown in depth reviews of watches , in the same vane as the one mentioned earlier.
So I wouldn't be worried about wearing one as a routine watch. Having some smaller vintage watches 34 isn't that small, even some of my more modern watches - my Memovox 35 mm max & my Nomos Tangente at 35 have great wrist presence & in no way would you think they looked dwarfed on my wrist.
So I'm with you being reticent about the size of these newer versions 39mm feels a little too large, and perhaps a step away from what you'd expect a dress watch to be. I think 36 might have been the perfect compromise in light of the market going big.
The dials look great, but for me feel a little flat without the applied markers of the 34 - which I think add character to the dial. Though I'd be happy to get an earlier version & have a solid caseback & gain a little more thinness. I'm also struck by the lug shape on the 34 side on they almost have a tear drop shape to them reminiscent of earlier JLCs.
Yes extra thinness is always special, but I've always found that JLC have a way of designing their watches so that on the wrist they wear/look thinner than they are - my Master Moon being a good example. Looked at in isolation it isn't as thin as it wears on wrist.
Both the more modern iterations of the Ultra thin look great, but I can't comment fully as I've only really seen/handled 34s. The ones I've tried have been the standard steel - which was great and a platinum version ( which from memory had the same dial, but had a great deal of heft & would have been a perfect under the radar watch - except at the time the price was a little too interesting!).
Ones I've seen online include the white gold with grey dial, which was stunning & the steel black dial which somehow comes across as a bit more of a modern twist. Finally there was a rose gold which came across as the epitome of a dress watch.
So while this has come across as a bit of an ode to the 34 - you need to get which ever one you feel drawn to the most. Because I like it is the best reason ever!
One final note though, in those price ranges you could have a whole sub collection of 34s - sometimes it's good when something is the road less traveled.
Happy hunting
Cheers
JML