Shimano's own argument is that it makes for faster down shifting and ability to have a limp home mode. It has been a long time since I've ridden so I might take to rapid rise much easier than most. Right now it requires I think about which one to use to get the correct one.
I'll install it on Friday and hopefully know by the weekend what I think about it. I just hope it goes on easy and doesn't ghost shift. I'll look at the installation manual to know which side of the gears gets the slight preference when setting it up. I know high normal requires you set it slightly to the low side of the gear. I saw a post from someone who was getting ghost shifting on a RR so they set it to require 1.5 pulls to go higher instead of just 1 (1.5 is normally halfway to the next gear but he said it was the only way to prevent GS.)