#2
theyre significantly better in my experience, ive had one for two years on my guitar and its been very solid.

not as good as an OFR (the JT580's are a bit stiffer when you push or pull on them) but i havent had too many problems at all
#3
How do you explain the stiffness difference? Any mechanism that pivots on a knife edge is as "stiff" as the components that contribute to its balance (strings and springs in this case). It has naught to do with the design of the actual trem. More/stronger springs and higher string gauge will make it stiffer, the opposite will make it less stiff.
Fender Japan Stratocaster Ibanez Pro540 Power Ibanez Pro540 Saber Ibanez 430S Ibanez S540 Charvel LSXIII w/GraphTech Ghost MIDI Parker Fly Artist Ibanez S1220 Mesa F30 Roland GR20 Roland Microcube + IBANEZ TREMS STILL SUCK!