If you think they are big, you should try lifting one.. need at least two people to rig them - fcking scary on a scissor lift with the sway from the weight!!
I guess it's cos of the ballast inside, but despite that they are worth every penny, I designed a rig with 60 of them on a circular truss about 10 yrs ago it looked amazing in operation apart from the "issues" we had (DMX nightmare) (had to have the main distro breakers replaced near on an hour before we were due to start the party as they kept tripping after ten mins with all of them struck)
Lovely stuff though.. I miss those days so much...