I'd only mount them center if you're going to be using them for park a vast majority of the time.
Otherwise I'd go 2cm or so back from center, better performance out of the park but still perfectly fine for
skiing switch, hitting rails, doing butters, etc.
Mounting center will not make butters easier. Having good fitting boots will be far more beneficial then where you mount the bindings when it comes to butters. If you've got sloppy fitting boots you could have the softest skis in the world and still not be able to butter very well because the power transmission from your feet/legs to the ski is inefficient.