What are rotary gears? Sturmey Archer 3 Speed I am confused by the three three-speed hubs that Sturmey Archer offers that are supposedly the same thing (3 speed hubs with a 177% range). I can gather that the S-RF3 is simply an Aluminum version of the AW, but what is the RS-RF3 main difference? What are rotary gears? Are there differences between all three that I am missing? Any help is appreciated 
(also does anyone know where to purchase these online)
Links

AW: http://www.sturmey-archer.com/en/products/detail/aw

S-RF3: http://www.sturmey-archer.com/en/products/detail/s-rf3

RS-RF3: http://www.sturmey-archer.com/en/products/detail/rs-rf3
RS-RF3 has a gear selector that rotates, instead of one with chain that is pulled. The rotating part is visible in service manual, look for "fulcrum lever set" and "shift actuator". As stated in comment, the supposed benefit is that no part of the mechanism protrudes outside frame.