I am very happy with the decision I made to purchase the studio display and would make the same decision again based on my experience for the past 6 weeks.
To put some context into the use of this, I work full time from home from this display and own a MacBook, iPad and iPhone. I have paired it with the Magic Keyboard, Magic Trackpad and Magic Mouse (yes I use the mouse and trackpad at the same time).
The screen is big, bright and a joy to use. I especially like the aesthetic on the desk and the simplistic one cable setup into the laptop.
In comparison to the iMac, I went through the same thought process as yourself and came to my decision based on the following points:
- The Studio Display is 132% of the iMac screen (based on purely physical panel size). iMac: 1,522cm^2, Studio Display: 2,010cm^2. Looking at them both together in store, the difference is huge. I really appreciate the space and the iMac 24 feels cramped in comparison now. I visited a store yesterday to purchase a watch strap and played around with them.
- My upgrade cycle is usually 2-3 years. Although I have a MacBook Pro and probably won't be using all the power. I can see myself picking up a MacBook Air in a couple of years to go with something more lightweight. I don't want my hardware and screen linked in this way and forcing me to upgrade down the line. Especially seeing as M1 is an 18 month old chipset at this point. I envisage the studio display lasting me at least 2 cycles of my planned 2-3 year upgrade pattern.
- Apple seemingly have removed the Target Display Mode with no intention of bringing it back. As soon as I decide I want newer hardware, I need to purchase an entirely new iMac, instead of being able to keep the screen and swapping hardware in a Mac mini/laptop.
Overall it was a pretty tough decision but I also think I the Studio Display sounds like it would be the way to go for you too. I guarantee you will enjoy using it, it is a fantastic product.