Yeah, ironically, the option to enable the Pump it Up style holds on SM4, is actually hidden WITHIN the theme metrics and is NOT in the menus yet. That, plus some other tweaks (such as removing the OK/NG signs since they aren't used for this). Yes, the freezes do act like on Pump it Up Pro, and I did find out that there IS support for "true" Pump style freezes (where you don't have to hit the head), but it's still got a bug, registering a miss when it passes through, but still adding to the combo. So of course, I didn't enable that.
It's based off the current theme from the current SM4 build, and YOU DO NOT NEED THE PUMP GAMETYPE TO USE IT, it's just some simple tweaks.