The late 2009 27" iMac I own. Took that apart to upgrade 1TB to 2TB. All went well but I had done a lot or youtube-ing researching before the attempted. And during the surgery process, I felt like I was some surgeon in the ER saving the Popes life.
One thing about iMac's, they really never become outdated.
I honestly have no issues, other than the hard drive space, to necessitate upgrading the entire machine. I now have lots of memory, and now all the drive space I need, and it does everything I toss at it flawlessly and fast.
Other than the idea of just something "new", I see no need to swap out my late 2009 27" iMac for the thinner and newer machine.
And that is the scary part having come from windows based machines of the past.
Where I was constantly upgrading this or that or the os itself.
It was like a merry-go-round. You upgrade the windows os, followed by upgrading the hardware to keep up. Then once again the os, followed by the hardware. And so on and so on. Round and round.
The new slimmer iMac has its place, sure.
And if I owned a smaller sized screen iMac machine, or was totally new to the world of apple desktops, I would certainly go with the new slim 27" machines no question about it.
But lesson learned, always spend the money up front and get the best machine available when it comes to apple.
Your spending the money anyhow. And yes they are pricy. But consider.... that iMac will last you a very long long long, long time. Unlike was the case with windows based machines.
If I were new at this and jumping into the world of apple iMac's a-new, I'd do whatever to get/order the best available.
Apple products are different. They are not built for the finicky. Unlike windows based machines, the apple iMac is not a "box" designed to be constantly user upgradable.
And that is just one of the so many reasons why I would never turn back to Microsoft for computing needs. Neeevvveeerrr!!!!!