I honestly don't know. Ranks are pretty new, so if it's been around a while, then probably not. I would think that 'class' would have nothing to do with Company Rank, but I don't know enough of the technical details.
Our current sigs show the logo of our starting cities. At this point it would be more relevant to show the company of the city we joined.
This is the loadstone info on my character. It shows my starting city, which I couldn't care less about, but is themed around the company that I joined (adders). Even if you can't dredge up our rank atm, if you could get company affiliation to determine the logo depicted on our sigs it would be great.