I have a 900D, 750D, and a 450D.
The 450D is great and one of the smallest cases that will fit an E-ATX motherboard. Well I finished my build... But I'm not actually using any of the room on the front. (two SSDs mounted on the back of the motherboard tray... So...
The E-ATX motherboards tend to be high end and usually have more features packed into them. Ultimately I still end up getting E-ATX motherboards.
A lot of things have changed in the last few years. AIO coolers are good enough for most overclocking. Partly because processors tend to hit a wall and even the best custom loops make little or no difference. They just aren't worth it, unless you really need that extra 100Mhz... So I don't need extra room for that anymore, And if I did I'd buy another 900D. Optical drives don't make it into my builds anymore either... So I don't need 5.25" drive bays. SSDs are better and cheap enough now. So I don't need 3.5" drive bays either... Although I could use them for 2.5" drives. But I would be happier with just 2.5" bays.
SO I chopped up a 450D (image) to make a 425D. The 3.5" drives could go too. I'm sure the designers at Corsair could do a much better job. But I've seen people looking for the smallest E-ATX case on several occasions and I'd like one in the future, preferably a Corsair 425D or something like that...