I think the new 2mm bump at the smaller end (38mm to 40mm) makes the smaller version more viable for some guys.
That’s the situation I’m in. Bought the 42mm in 2015 and have used it since. I have small wrists but ultimately went for the larger size because I thought the 38mm was a tad too small. Now that there’s a slight bump I’ve decided to go for the 40mm.
I attached the pics of my 42mm and my girlfriend’s 38mm. Hopefully the 40mm will be perfect for my wrist!