They play bigger than the static weights would suggest, maybe even bigger than the swing weights, although swing weight is supposed to account for a different mass distribution. I play with a leaded 18x20 IG (to about 340g) but the 300g mp seemed more solid to me.
At our demo night seemed like some people really liked the new versions and some the old version. I'm in the new version camp -- I think it's a great upgrade. There isn't anything about the old one that I like better.