[Gracana]

> probably as big as switching between BSDs

No, it's not. You can go from one GNU/Linux distro to another GNU/Linux distro and you're still gonna find a GNU userland and a Linux kernel. Base userland and kernel differ significantly between BSDs.

[cat199]

plus - native binaries can be copied between one and the other and run natively without any emulation layer provided the c library, kernel version, and other libraries are reasonably similar.