Hi, I've come from playing under macOS on a MBP - as Mr Ninja said, you can't transfer your account or use your existing HOTAS. For me, it's been great fun starting fresh, so I'm happy to not transfer my commander.
I've purchased a PS4 Pro purely to play E: D. The graphics are a definite step up from playing on macOS, partly as I previously had to turn settings down to get a consistent frame-rate. If you were bootcamping, then I'm guessing it's equivalent - although the resolution will be locked to 2K (not that you're likely to have been playing at 5K). The consistency of the game has been impeccable, not seen a single lag or jitter anywhere. I've even not seen any detail being filled in as you approach (e.g. the back of the slot). Generally, it's more immersive and I'm very impressed.
The best bit about it is remote play. I'm playing from my MBP and it feels just like I'm playing locally, the client will even turn the PS4 on remotely. No noticeable lag, and it's full 1080p assuming you have the PS4 Pro. This is important as the stock PS4 will only do 720p. I can't remember if the iMac is a 16:9 or 16:10 ratio screen, but if it's 16:10 like the MBP, then there will be small black bars top and bottom, but I don't even notice them. I play with a dual-shock, so I don't know about remote play with a HOTAS.
If you're interested in remote play, then I posted a couple of pictures and more detail in a thread on the Mac forum (So long, and thanks for all the fish).
Be aware that you'll need a PSN subscription to play in Open play.
Pros: a better and more consistent experience, with Horizons content and a (more) guaranteed future.
Cons: starting again, paying for the PS4, game, future expansions and a yearly subscription to play in Open.
Let me know if you have any questions for me.