I ask because Debian has a FreeBSD "port". That is, it offers the Debian userland on top of the FreeBSD kernel.
So, depending on what you're looking for, you might be able to gain access to the best of both worlds.
If you're after the FreeBSD experience (i.e. the community, the BSD command line utils, ports, and the preference for permissive licenses), then I guess Debian/kFreeBSD really isn't of any interest to you.