I use Debian on my laptop, and FreeBSD on my server, but I wouldn't touch GNU/kFreeBSD with a ten foot pole. FreeBSD kernel with GNU userland and SysV filesystem layout is the worst of both worlds.
I'd rather see the inverse: a Linux kernel with BSD userland, filesystem, and ports. But that doesn't fit with Debian's strengths as a package repository. Installing packages to different paths on different systems is not really feasible. Using ports means Debian has nothing to contribute, since it completely replaces the Debian package system.
On the other hand, swapping out just the kernel is a natural fit for their system. All they have is a hammer, so they found a nail. Unfortunately it doesn't result in a very appealing OS, since the kernel is not really the selling point of BSD. It works, but it's nothing special. The magic is in the BSD userland.
I like the solidity of BSD and I love ZFS, but the ports system always felt surprisingly flimsy (coming from Gentoo I was expecting it to be just like portage, but it's a lot more ad-hoc and breakable) and I never got on with the BSD userland - I mostly work with alias ls=gls, cp=gcp and so on. If I set up my server again it would probably run GNU/kFreeBSD.
