Don't forget CSR charges you got $75 for each AU. IMO that should absolutely be factored into the household cost of holding CSR.
Many people in this game have other cards with overlapping benefits with CSR. I find that between my Amex Platinum and Chase Ritz Carlton cards, I have little need or justification to hold a CSR card. I do have CSP so I can easily transfer points into one of the travel partners programs.
To each his own. I know lots of people who are very happy with their CSR. Those tend to not to be the churning type from my anecdotal experience.