[DeltaMac]

Even if Apple makes it possible to load and use a variety of non-Apple operating systems, that doesn't mean they have to provide direct support, or even answer any questions. Why should they?
Apple offers the Boot Camp software, but they don't provide Windows software with that. And, Apple has said from the start of Boot Camp that they will not provide support. They do support in a limited way, by providing install troubleshooting hints, and updating the Windows drivers as needed for the Mac.

Wouldn't it be more productive to go to a Linux support site for assistance with your Mac/Linux install questions? And, there's plenty of Linux users, even on this site, that can supply you with opinions/experiences that can directly relate to your needs.
That would be better than hoping that you will find a Linux/Unix expert at an Apple store. There are some of those, to be sure. And an Apple Genius will have more than a passing knowledge of Unix needed for support of OS X. Read that last sentence carefully - that may mean that someone at an Apple store might have other knowledge, but not used for their job. Apple already has an OS, and they want to continue to sell that.