FX Anyone have an FX Dynamic Compact Takedown?

Simple answer, no. As far as I know, FX has not come out with a barrel kit that would allow for a simple change of the barrel/shroud/plenum and probe. Plus, since it has the over barrel plenum, you also have to completely degas the rifle to remove the barrel assembly. A caliber change can be done with a barrel liner and other caliber specific parts. Either way, it may as simple as a caliber/barrel change on an Impact.