The fact is Linux is not OS X. And OS X is not Linux. One does some things better than the other and vice versa. I run a mixed environment. I have a desktop that primarily runs OS X and a laptop that primarily runs Debian Linux. So I thought I'd compare the two and show you the ways which Linux has helped me.
On OS X my most used applications are TenFourFox, iText Express, iTunes, Mplayer, MacTubes, and Transmission (it's always on in the background. I'm on a private tracker). Incidentally, all of those applications have identical or very-close-to-it counterparts on Linux. I also commonly use Cyberduck, ToyViewer, GIMP, SABnzbd, TenFourKit, and GarageBand. But sometimes it's not enough. One limitation I have is I don't have a widescreen monitor, so it's difficult to play video and do other work simultaneously. That's where my Linux laptop comes in. I use it for streaming media, Youtube, etc., and it has its own dedicated processor so my desktop's doesn't get bogged down playing a webisode of The Guild. It also has Pithos, which is unavailable for OS X, that streams Pandora radio.
Another thing I turn to Linux for is LibreOffice. LibreOffice on OS X is too dog slow (
Lately I've been getting my feet wet with music production and trying software synths like Yoshimi and Phasex, and sequencers like LMMS and Qtractor. Some Linux DAWs and synths are more polished than others, but the range of choice is amazing. And as far as music playback goes, I love Audacious's xmms interface and hate that there's nothing like it on OS X.
My point is, nobody who says Linux will be bad for you is making a definitive statement, 'cause I'm right here and Linux for me is working nicely. Here are a few screenshots taken with Shutter (a Linux Skitch replacement now that Evernote has destroyed the original). I find the dark theme much easier on my eyes.
I had to use -vo x11 to capture the Mplayer video, 'cause with the xv default it showed up as a transparent window.