Yes, all the damage would be empowered so that each berry would do (1d8 + CL) x 1.5. An interesting part of your argument would now make me ask, would Warmage Edge get empowered on top of that? I believe that it would not be, because it isn't an integral part of the spell, but is instead tacked on after the fact, making the equation (1d8 + CL) x 1.5 + WE, and not (1d8 + CL + WE) x 1.5.
Still, even knowing all this, I am still unsure whether the 1-8 berries the spell creates would get empowered so that you could get upwards of 12 berries in an empowered casting.