Well, I guess this is pretty much the end of this thread.
After weighing up the pros & cons for days, I decided to keep on playing with NIKE Vapor Fly Sets. Who knows... Some day, I might change my mind again and go for RSi2s, but for now, I believe this is the right decision for me.
I'd like to thank all of you for giving such valuable thoughts, especially Robert1893 who spent his own time to conduct the experiment with RSi2 by himself, and of course, Solarflares who provided incredible and profound insight into the subject.
I hope you like my gifts and I only wish I could give more...
Good hitting, everyone!
Simon