I had CB for many years when they still had the 60-day billing cycle. I dropped the card when they discontinued the 60-day biling cycle and converted to MC. Truly, the only thing that had it going was the 60-day billing cycle, primary car rental insurance, and live rep.
I had little use for all the other benefits. The airport lounge access is extremely limited (Miami and Newark), never had to use the golf benefit, and used the purchase insurance once. I had very limited experience with the concierge, but recall it was serviced by VIP Desk, the same providers for the Citi Chairman Card and other Elite Mastercard products. In my opinion, it was never worth the $300 annual fee.