see that's the thing tho -- there is a LOT of misinformation roaming around out there in various forums (including these) that claims the iMac isn't user serviceable by the layman. *full disclosure* I built my own PC boxes for years and years, and I'm really not all that Mac hardware-savvy despite having owned one for several years.While nice, thats not new. Same with prior iMacs. Very easy to access.
YES this ifixit teardown is highly useful to me because it looks like, so long as you're careful, it really does not seem that much more complicated swapping out parts than in some of the older tower PCs I fiddled with.
honestly if you read through that ifixit, not only do they show how to remove the optical drive, but they even provide a link to a slot-loading blu-ray drive to replace it with. So ok, this machine doesn't come with BR installed. You have 2 choices: video in from your external BR drive (which is apparently easily do-able, you just have to buy the right plug and you're set) or roll your own using the ifixit article as guide.
I mean, I know it's likely not a trivial task, and sure it would be nice to have it all BTO but it beats the hackintosh route (oh and don't even get me started about Windows machines... they suck, which is why I abandoned them!)