With it having been since late last year when trying out the Debian GNU/kFreeBSD variant that pairs Debian's GNU user-land with the FreeBSD kernel in place of Linux, I ran some fresh trials on one of our test-beds this week.
I've been toying around with Debian GNU/kFreeBSD for almost a half-decade and it's been progressing nicely for those looking to take advantage of Debian's vast package archive but looking to use a BSD kernel either for philosophical reasons, taking advantage of features (e.g. D-Trace or ZFS) not found within the mainline Linux kernel tree, or other reasons. From my perspective, it's just another interesting test target and shows how well Linux can compete against FreeBSD when having matching user-space environments.
In the next few days I will have up some tests comparing the latest Debian GNU/kFreeBSD "testing" state to the matching Debian GNU/Linux Jessie state along with Ubuntu 14.04 Linux tests and other comparative Linux distribution tests from the same physical system. The tests for this article are just a straight-forward comparison when installing Debian GNU/kFreeBSD 7.5 Wheezy and then installing the latest weekly snapshot of Debian GNU/kFreeBSD testing for what will become 8.0 Jessie.
Compared to 7.5 stable, the latest testing state is packaging the FreeBSD 10.0-1 kernel by default over FreeBSD 9.0-2, X.Org Server 1.15.1 in place of X.Org Server 1.12, Mesa 10.1.2 in place of Mesa 8.0.5 (but the Radeon KMS support isn't enabled by default), and GCC 4.8.2 over GCC 4.7.2. The UFS file-system is still the default during clean installations of Debian GNU/kFreeBSD Testing and not yet ZFS.
From my testing thus far the Debian GNU/kFreeBSD state is quite good and has been working reasonably well with the Xfce desktop and for most simple end-users they wouldn't even notice a different kernel is running underneath. The main problem for most users would likely be Debian GNU/kFreeBSD's more limited hardware support.
All benchmarking under Debian GNU/Linux and GNU/kFreeBSD is done using the open-source Phoronix Test Suite automated benchmarking software. All testing was done from the same Intel Core i7 3960X Sandy Bridge Extreme Edition system.