Exploring options and alternatives to buy a new monitor vs trading brand new mac mini for imac.
My spouse and I both use iMacs for Lightroom CC and PhotoshopCC for image editing. We are both ardent amateurs, not working pros.
They work fine with the Retina displays - get plenty of Ram, at least 16 Gb these days I think, and plan on some kind of external storage media with several back ups.
My spouse uses external hard drives via USB 3.0, and I use an external RAID 5 array. Both work. Ultimately it depends on your needs and your budget.
I previously had used a large LG monitor that I still like a lot.
The new Mac mini has a lot of potential for CPU power and RAM if configured that way. I am thinking it's my next desktop. The one weakness of the Mac mini is the built-in integrated graphics (Intel UHD Graphics 630), is weaker than on the MacBook Pros. This can be addressed by adding a Thunderbolt eGPU if you have the space. But that is not cheap, and the iMac has a better GPU built in.
I think the Mac mini integrated GPU is enough if you spend all your time in Photoshop and Lightroom (or similar) with one monitor. That's why I'm still thinking of getting a new Mac mini to go along with the great monitor I already have. It's really the video editor/3D/multiple 4K monitor types who need a better GPU. But if you do add a Thunderbolt eGPU to a current Mac mini, you can bring it within striking distance of the more powerful Macs on applications that actually make use of a GPU.
Whether you switch to an iMac might depend on what monitor you would be willing to get instead. Since I have an accurate wide gamut NEC with some features that an iMac monitor doesn't have, I don't want an iMac, I just want to connect my nice monitor to a Mini. Similarly, if you are looking at maybe buying a monitor that exceeds iMac features, you can just keep the mini.
If an iMac monitor would be a definite upgrade from what you have now or are thinking of buying, swapping the mini for the iMac could be a good move and you would get a GPU upgrade too, as long as you stay away from the cheapest iMac, don't skimp on RAM, and if the price of all that is still OK.
A bit late to the thread but this is exactly what I have done this year to replace my old iMac
An i7 mac mini with loads of RAM and a good sized SSD paired with the BlackMagic eGPU and a beautiful LG 32" 4k monitor. This still came in cheaper than the same spec on a 27" iMac plus I get more flexibility around screen. The Blackmagic eGPU was an interesting choice as you can get more for less but it runs totally silent which is something that cannot be said for other roll your own eGUS setups
Running Lightroom to be fair only touches the GPU (internal or external) once you go into develop mode. Photoshop of course laps up that external power nicely. Overall I am really happy with this setup although I did struggle for a while whilst trying to utilise an external Drobo unit. Not sure if it's a driver issue or what but it made my setup really unstable. Now I have replaced that everything is good.
The mini should be a serious consideration if your primary focus is still images