Re the chromed stays - I like the look of them too. But I am not certain how great the quality of the chroming is, and my feeling is that it's not top notch. Incidentally, the chrome on the handlebars is peeling in some areas - what is the best way to stop that?
I have been trying to find out what the tubing is. It is labeled "LUXTUB" which, as I understand it, is proprietary to Mercier. Judging by the components that have been put on this bike, I do not think it is cro-moly. However, the bike is surprisingly light and I have read others describing Mercier's mysterious tubing as "having a cromoly feel". So, in short, I don't know - but whatever it is, it feels superb.
In general, what I like most about this bicycle is the intangibly wonderful ride quality. It is so stable and "cushy" for lack of a better description - while also being light and fast. The comfort of an English 3-speed combined with the maneuverability and lightness of a French roadbike.