Yah, this actually brings up a good point. The fact that they don't pay more for the higher ranks means there's no real incentive to wear the biggest signature possible for your rank. I wonder if their bot is careful to check this.
I was under the impression that they don't mind if people use a "lower rank" signature. IIRC correctly some hero member stated that he preferred to use the senior member signature. I don't mind much, to me the hero member sig looks good

Onkel Paul
Interesting. I mean what you say has logic because they pay the same for all sigs all ranks. Nevertheless, if I had known this while I was participating in this campaign, I would have probably used the full member signature simply because it's smaller and less intrusive. If they are paying the same for all sizes, I would choose the smallest size (personally). If everyone took the same approach, it actually might force bitmixer to pay more for larger sigs (which would be a good thing, IMO).