The other advantage is that the dynamic version can be used on any figure, as some of the pics of M4 in that same bikini (bottom) can show.  You don't need morphs or rigging to get it to fit.

RosemaryR
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"This...this is magnificent!"
"Oh, yeah. Ooooo. Aaaaah. That's how it starts.
Then, later, there's ...running. And....screaming."