The C is the smallest chamber version of these, and the 5 is in the middle of the range for tip opening. I own a B5 and an A7. The B5 works fine, but I wasn't all that excited by it. The A7 - largest chamber, largest tip opening, was a lot more interesting to me. I still have them both, but I bought a second hand Selmer Super Session F, which is what I now mostly use on my alto. I'd probably have been quite happy to just stick with the A7 and get used to it.
Really, my point is, the C5 (which I haven't tried) isn't representative of the whole range, except that it's well made and quite capable. I'm sure you didn't mean to imply that, but it might be what people take away from reading this.
The A7 and B5 are very different. The A7 suits a softer reed, because of the larger tip opening - actually larger than my Super Session F - which is good for note bending, but not so good for tuning stability on the high notes. Good fun though.
The different chamber size probably does contribute to a different sound, which they definitely have. The A chamber size might have been more what you wanted, and maybe closer to the darker Vandoren in sound.