I had the S400 and S300. Both Cases are in my opinion to big and heavy. Nearly 2kg empty and 1,6kg. And the others are even heavier.
These Typ of cases are bulky. It’s not a Console form factor.
And even with the two Fans the heat is collecting in the middle of the Case. The backplate of the GPU is to close to the CPU cooler!
I didnt have any issues with that in the S400. The main problem is the location of the PSU extension socket, which blocks most of the area above the mainboard, so cooling that is a very hit-and-miss thing. If you go with anything but the Air Slimmer 120, cooling is sub-par. And even then its just so-so. I did use a combination of P12 Max + Air Slimmer 120, so this "heat collecting in the middle" thing did never occur with my setup, but the MB side still got very warm.
Weight-wise, its okayish, could be better, but its all a thing about availability and costs - the S400 is much easier available and also, costs less, than say something like a FormD T1, a Custom Mod case, or even the cases by SFFTime. I only ditched it because of the heat situation with my CPU. Remember, not everyone is located in eg. the US (I'm in Europe).
Going back to topic:
Currently I'm both eyeing the U-ITX and P-ATX, for a potential mix of high-tier CPU (7950X), mid-tier GPU (RTX 4070), mid-tier but premium PSU (HDPlex GaN 500) and "as much CPU cooling as possible" (figuring out 120 or 240 AIO _or_ custom loop).
cu, w0lf.