I own both watches and I would not want to miss any of them. I was really happy when IWC launched the 3905, because they transformed the design of the 3902 into a size that I could wear. The reduction from 45.4 mm to 43.5 mm might not sound that much, but in the flesh it makes all the difference if you have a small wrist (like I do).
The 3905 has not so much to do with the vintage Yacht Club watches, because the never were a part of the Portuguese line, they never were Chronographs, the never had a rubber strap, etc. But nevertheless the 3905 is a really great piece. It wears very comfortable. You always feel that this is no lightweight watch and it is far from being an ultra slim construction, but in itself it feels just right. The combination of a very high quality rubber strap with a folding clasp is a good feature.
If you want to combine the watch with a fine suit it might be a bit too far on the sporty side, mostly because of the rubber strap. But besides this, it is a very nice companion with nearly any type of fashion.
So I really can recommend this watch to you without any caveat. The ardoise sunburst dial looks astonishing and the ca. 89361 is very nice to look at either. It is one of my most precise watches, running at +3 seconds per day.
I am completely happy with it.

