Ever since I wrote this, I took my wife's imac to just try it out. Like I said I LOVE my rMBP. She has a 2014 iMac so it's very good. 32gb of RAM i7. I got to admit, I'm a bit disappointed. I'm trying Parallels but everything is so buggy. If I do fullscreen and launch another VM in full screen and close one of them, the last running VM takes over the desktop. So it's like the same thing is on two spaces but you cannot open any windows or do anything else. You have to get out of fullscreen for it to "release" the desktop. The mouse cursor never changes properly. Half the time it looks like the OSX cursor in the VM so things like scrolling doesn't work. If you move the mouse in big circles it seems to switch to the windows cursor and everything works, but I don't want to do that all the time. When running the big VMs (SQL, Visual Studio), at times (not sure what causes it), I get the spinning candy or beachball or whatever it is. I have to hold power button and restart. I am not assigning too much memory or processor so I don't think it's a resource issue. I tried VMWare Fusion, definitely a lot more stable but same cursor issues and spaces issue.
She has a the flash drive in there but it feels slower than windows. Little things like launching onenote takes 2-3 seconds as opposed to instant in Windows. Also no windows snap feature.. didn't realize how often I use that. It's a lot easier snapping a window to the top to maximize it rather than trying to click a really really small green circle which takes up a full screen and the animations/getting it full screen takes closer to 2-3 seconds to do. I guess I'm used to things being instant.
I DO love the interface however. Something about the font, the "task tray" in the top-right hand corner, the dock. But the bugginess is killing it for me. I received a call from my iPhone and it called on iMac. I answered but no one could hear me, it was too quiet even if I yelled. I checked all the settings and ran some tests and nothing is broken. It's also insanely delayed for when people tried to listen to me (when you say something the other person doesn't hear it for 2-3 seconds) which causes a very awkward conversation of talking over each other. Definitely not like they showed in the keynote. Wasn't instant either, took about 4 rings before iMac started ringing.
You are right about the screen. It is very good, great color reproduction. Only thing, I have to close my blinds because the glossiness is insane and gives me a headache pretty quickly. She has a newer iMac (the thinner one), so I guess screen is supposed to be better, but it's still a mirror.
Sorry about all the complaints, but I'm convinced now that I won't be using an iMac for work. For personal stuff, browsing the net, watching youtube videos, reading news, maybe even playing basic games, etc, it's beyond perfect. Safari is snappy and smooth scrolling feels nice. Love the keyboard and the mouse (although it feels insanely laggy, but I'm sure I can get used to it).
I guess I have to do a time machine restore (very nice) for my wife's stuff to get back. I did a clean install of Yosemite.
But thanks for all your answers. Was really helpful.