I just bought this shaft in the 100 flex model after snapping my [seriously] old Easton Z-core. That being said, this is the lightest shaft i've ever held, but I'd probably say that about an Easton Stealth S3. It is honestly pretty light, though.
As far as gameplay, this thing is amazing. Excellent feel when shooting the puck, and way better accuracy than i had with my previous shaft. However, the previous reviewer is correct in saying just any old blade will not cut it in this shaft. I stuck a wooden blade, maybe $25, into the shaft since that's what I had laying around. Good feel, but I was definitely able to notice power bleeding away from the blade. I'm planning to buy an Easton ST blade to stick into it, which should fix the problem.
Bottom line, after the very first shot i took with this, i wanted to buy another. It really is worth every penny.