I have a new 36" RCS sitting in my dining room at the moment, waiting for the kitchen remodel to wrap up. Like you, CentralMA, I couldn't discern a functional difference between the RCS and baseline RNB other than the 22K BTU burner, so decided to put that extra thousand bucks elsewhere. If it turns out I really need a 22K BTU burner, I'll replace one of the 15Ks.
BlueStar won't sell you a 22K burner unless you can prove you own an RNB range, but people on eBay will, as (I'm told) will some online appliance stores. The going rate seems to be about $150 (the 18K is the same burner, but you use a different orifice to upgrade it to 22k).