I hate to disappoint you but if you're wearing a black or very dark navy tux, only black shoes would work. Why don't you just buy the C&J Weymouth cause they fit you? Unless you're renting your tux, you do need a pair of black shoes and I'm sure the Weymouths are a very solid pair that will last you a long time. Also, there will definitely be occasions which call for black shoes only.
The Beijing is part of the City Line which AFAIK has been discontinued. It is made to a lower standard and offers polished binder only.The Houston is part of the Office Collection which is made to Custom Grade standard but slightly cheaper than the Classic Collection shoes.
Well, since we've been talking how one should price brand new G&G shoes for secondary sale, thought I would chip in with this example(not mine of course);
NIB Gaziano & Girling Grant With Lasted Trees
Will Ship To: Anywhere