Is most of the additional weight via the use of the "Seattle Slug"? If so, then you can, if they make the option for the Gen 4, add even more weight with the heavy slug.
It seems to be although it's not really weighted. It's a block of what looks like aluminum that's drilled and tapped. I'd like to see them make a brass insert instead and bump the weight up. My guess is they will but are unsure about demand so they just released this version for now...