OK; I've had my EMB 12 degree, square faced head with the Axiv-X R flex shaft @ 45.5" for nearly 2 months now, so I can report without sounding like puppy enthusiasm about a new chew toy.
This sucker is LONG. This sucker is STRAIGHT. The shaft really kicks, but seems perfectly controllable in my hands. I'm a mid-50's guy with a relatively flat 95-98 mph swing, and I need a bit more loft than average to get enough carry.
I am carrying this over bunkers I used to avoid. I am outhitting my buddies by 20-40 yards on comparable drives. I kid you not; this is by far the longest hitting driver I've had. The only others that were close were a Golf Gear Tsunami with a 50 gram 46" shaft I couldn't control several years ago, and a Wishon 919 THI with an X-Con 6, but the Epon EMB is clearly the longest. I can get a bit of fade or draw, but it really wants to go straight.
Despite the relatively low weight and slightly longer club and all the flex, this shaft is very solid and predictable.
I paid a bundle for this club, but it was worth every penny.