I'm in a similar scenario, we basically get freedom of choice over OS, with the caveat of being responsible for our own installs of course. This works well small scale with competent devs you can trust to take care of their own OS (we help each other out if needed obviously, but the point is that you become fairly self sufficient in that respect, no "IT dep" needed).

I know there are reasons this can't happen at large corporations such as security... more to do with contracts and culpability than measurable security improvement AFAIK.

I can't quite imagine _not_ having control over my work environment in this way in a job anymore and do greatly appreciate it. It's not all about familiarity, there are many objective reasons using certain proprietary OS can be a significant drain and inefficient, even more so for development work. This freedom would be a significant factor in considering a new job for me, even over pay because it's a big part of my "happiness" and "sanity" factor in the job.