R/T on Dodges isnt a performance option, its a package level like LTZ or SLE with Chevrolet and Ford. Although the R/T option does generally get you the more powerful engine, its often the only way you can get a decent version of a Dodge product.
...If we go back in time, say 1968, Chevrolet had oodles of SS vehicles at the time... Nova SS, Camaro SS, Chevelle SS, Malibu SS, El Camino SS, Impala SS etc...
Today its the Cobalt SS (S/C and N/A), Malibu/Maxx SS, Impala SS, Monte Carlo SS, Trailblazer SS, and Silverado SS...
So technically, there are the same ammount of SS vehicles available, but today there is a wider selection of model types available with the SS package. Word is that the Tahoe could soon be given the SS makeover complete with the 400HP 6.2L V8 out of the Escalade and the 6-speed automatic, the slight possibility of an HHR SS, and still the Camaro SS...