I can vouch for the 900's airflow. Damn thing is colder than the grave inside. The downsides I encountered were:
1-ZERO room for adding CCFL lights in such a way as to conceal them nicely.
2-F*cking upside-down orientation makes running the cables a pain--most people Dremel the hell out of their cases, which you may or may not want to do, but it helps a ton. Ask around, the 900 guys here have some great cases.
3-Permanently wedded to the blue-light motif. Can be changed, but it's extra work.
4-Damn 5" bezels are a real hassle to align.
5-Too many screws, too little time.
Things I loved:
1-20cm vertical blowhole. Just...wow.
2-Quality stock fans, very attractive LED lighting.
3-Fully-grated front makes for astounding airflow.
4-Effortless motherboard and PCI/PCIe device install.
5-Whisper silent unless you set the fans to high.
I used my poor old Antec on my girlfriend's comp, and it works great. She keeps it on the floor, so it's become a dust magnet. I moved over to a NZXT Apollo and quickly grew tired of the over-the-top exterior (sorry ThatGuy, I do still like yours). Right now I'm waiting on a Lian-Li V1000B to arrive with a window and 80mm fan in the top, along with a pair of Yate Loon 120s, a few CCFLs, and some LED cannon lights. I eventually decided I like it to be simple on the outside, flashy on the inside.