Hmm, I'm appreciateive that folks have helped me think about this.

Yesterday, when I placed my order, I had chromeline exterior in it. Now that I think about it, I really want black and not chrome mirror caps. Too bad, though, I would've like the chrome on the front and back.

A guy on mini2.com posted these pics of his SS with chrome bits (no mirror caps ala European options) and I've compared them with SS/B cars I photographed here in AZ.

 

Get the chrome line pkg if you want the chrome bits. Someone will love to trade out their mirror caps plus some cash -- I hear they melt for them in the UK.
Besides you are giving up multiple parts you want for the sake of one. I think you'll pay much more aftermarket for all the chrome pieces.