[Catbird]

This probably won't answer your question exactly, but the QPQ finished slide has been discontinued by Walther and is being replaced by a Titanium coated slide; same silvery color.  From pics I've seen, the slide is literally marked "TITANIUM COATED".

 

[Catbird]

Regarding the aesthetics:

While many people don't, I personally like two-tone, silver over black pistols. I was really looking forward to the new titanium coated P99s as a possible purchase, but I find the rather large  TITANIUM COATED printed on the slide to be unattractive and kind of tacky.

Of course, as always, Beauty is in the eye of the beholder.