lalitk,
I've heard the Canterbury and other coaxial Tannoy speakers and liked what I heard. I just did not consider them in the discussion because they I did not consider them to be a single, full-range driver. But, they are certainly great sounding examples of fairly highly efficient speakers that are easy to drive and can be run with low-powered amps. I also agree they are quite nice to look at too.
I have a friend who is now in the process of building a system using the coaxial Altec 604 drivers from Great Plains Audio. At one point, he considered an Onken cabinet, but, the available designs for this driver specify a 360 liter cabinet (one and half times the size of the Canterbury's Onken cabinet) and this was too large to be practical. Too bad, I like the sound of Onken bass reflex speakers.