I have considered this lens in the past as it has good reviews for what it is, but was reticent because of the weight so i'll give you advice i give everyone wanting new equipment like this... go pick the thing up attached to your camera and have a play for 10 minutes or so around the shop (or just outside if the guy lets you)...

"In every colour, there's the light.
In every stone sleeps a crystal.
Remember the Shaman, when he used to say:
Man is the dream of the Dolphin"

Rich Meadows Photography