I need Lightroom.
Photoshop plugins. Integration with Elements (or CS6, if I ever decide I'm bored of having £600). Integration with my online services (Zenfolio, Flickr, Facebook, etc).
It's where my photos are. It's what I know how to use effectively. I'm interested in photography, not learning how to integrate a load of programs on Linux to kindasorta approximate a solution I've already got.
I had a massive sense of humour failure just trying to get the drivers for a cheap USB slide scanner installed (you know the drill - device made in china, software written by students, the whole apparently having undergone a testing programme that in its totality was "it worked once on one PC").
Computers in themselves are boring to me now (and I'm as surprised as you that I've arrived at this conclusion, but there you go). It's what I can do with them that's interesting.
BTW, I'm pretty much averse to both KDE and GNOME these days. Just looking at those digikam screenshots gave me hives. Who the shit wants buttons for "rotate right" and "rotate left" occupying space that could be used for your actual picture? Anyone shooting RAW has a camera that puts things the right way up automatically. Hell, a dedicated "straighten the shit out of my horizon" button would be more useful.
I had UBUNTU whatever-the-latest-is on my laptop for a while, and I didn't like it at all. Nothing specific, just an overall negative reaction. I must confess I wasn't terribly enthralled with the "added value" of Amazon search results when I was looking for things on my local computer.
Yeah, Lightroom is a dealbreaker. I know there are alternatives, but I'm simply not interested. My workflow is Lightroom. My catalogue is Lightroom.
TBH, I might just keep the iMac until it dies a few years hence, then just spend my share save (3 years from last month, will gross about £4K) on a second-hand 5D Mark 3, a 17-40 and perhaps a fast prime (<-- interesting), and review what the hell I'm going to do about a computer (<-- not interesting) then.
I was seriously looking at Chillblast (stupid name, good products) custom PCs yesterday. My main problem is my requirement for a single, massive monitor (27", 2560x1440) which seems to punt any decent system well into iMac price territory.