Ok, so we have a lot of things rolling out here.
SSD:
You should read this before buying a SSD unit:
http://techreport.com/review/26523/the-ssd-endurance-experiment-casualties-on-the-way-to-a-petabyte
The TechReport team set up an edurance experiment to test the reliability of a SSD unit, and - as expected in my opinion - the Intel and the Kingston were fine, because they are a long time in the market since they are experts in flash memory.
Considere buying at least 120GB of capacity of SSD and install the OS in this unit, and buy at least 1TB of HDD for you personal stuff. Install all applications in the SSD, and change the preferences to be stored in the HDD. Also, move your personal directory of the OS to the HDD. If you are not buy a 240GB SSD, then do NOT install your games inside the SDD, because nowadays a lot of games are easily 30GB+ and you will feel the lack of space sooner. In other words, if you want to load the games faster, buy a 240GB of SSD.
Case:
I compared the cases:
http://www.corsair.com/en-us/obsidian-series-450d-mid-tower-pc-case
http://www.corsair.com/pt-br/carbide-series-400r-mid-tower-case
I think the 450D is better, but I'm not sure. I didn't understand what you said about downgrading to the HDD. The point is, the 450D has more internal space.
Please, give more details for why you changes the case model.
PSU:
As @rockie_ said, change the PSU. The GTX 970 requires a minimum of 500W, but we would like to give it a lot of "space", so your PSU won't work overcharged. Here is a good list:
http://pcpartpicker.com/parts/power-supply/#m=11,14,56&W=700,1600&e=3,2&sort=a9
The CX family may have had a lot of problems reported, but it might bee just some "local" issue that you should not worry about. Probably, in some months the reports will drop.
Monitor:
I didn't notice much difference. The Acer has a littler, very little reponse time difference, but the contrast ratio is higher. Also, the viewing angle is wider for Acer. I would piick the Acer.