TANNOY: Westminster, GRFs, and Canterbury?

"I am giving serious thought to changing my little ATC SCM7s for something with a bit more scale having moved into a house with a much larger listening space than in the old one. Various comments and threads on here have got me interested in the gentleman's speaker choice; Tannoy.

How pronounced are the sonic differences between 10/12/15 inch drivers or indeed between red/silver/gold? My understanding is that the cabinets are not really worth much unless they are of the large horn-loaded variety, is there any preference between e.g. the Lancaster or Chatsworth varieties ?"