I love them both. The RT was slower. Just made you want to 'relax' and cruise about, The added weight of the fairing and the far greater wind resistence of the windshield, lower fairing (scuse my spellling, I'm dyslexic and cant be fussed to use the spell check!!) all added up to slower. But hey, what the hell it was quite fast enough for a 20 year old bike with a 50+ year old on top. Great protection though, and given our 'English' weather and the rain and snow and rain and sleet and rain, and the a sunny bit, it was invaluable and a real all year bike. Rode it in minus 5C and 3 ft of snow! But did it get HOT in the summer. Shins glowing red in traffic. But in the winter what lovely warm legs. Mixed blessing.
The RS is much more sporty fun. I wonder if the computer box was programmed differently by BMW for each model? It really provides what our Police call 'rapid progress' (well it is 20 years old, shaft drive and not Japanese, so it is a relative fast) but none the less it just wants to go faster. Cruises at 90mph without a bit of hussle, and its 'roll on' from 55 to 100+ is just sublime. No fuss just a lovely big hearted surge. Not like a rice burner at all. At 125+ I remember I'm not rubber and that the machine has had a number of not so caring owners. Time to show respect for both of us. The fairing is still great, and gives more cover than I would have belived. Without the lower bits, it also gets less hot. But yes there is less protection. Not so easy to ride at first and a bit of a pain in the wrist , but it does seem to handle better at higher speeds. That long wheel base and big wheels kick in.
Enough, I need a beer (its saturday night here - 9pm.) Cheers B.T.B.