I have one of these. There is a few things to worry about with them.
First they are HEAVY. Fully loaded the thing weighs in at about 300 pounds. The rails on it are static. The chassis and rails are designed to be put into the rack and never removed. Second, the chassis is the longest thing I've ever seen. They are easily 6 inches longer than anything else I have. The cable management sticks out 4 inches beyond the face. It didn't fit in the rack I was hoping to use them in.
The fans are big (about 2U sized fans) and they are fast and they are loud. Imagine the whiniest 1U fan and then turn up the sound to 11. The fans are shared between all nodes. If one node misbehaves or is absent, all the fans(power supplies and cooling go to max). The nodes don't have to be on, but the BMC for each node needs to communicate or the fans will go to the max. Likewise if one node ends up really loaded and starts heating up, the whole thing does start spinning up. However, even under maximum load, I never got the chassis to spin up to max like it does on boot.
Make sure they have the cables for the hard drives. Those cables are not standard on the nodes I have. There are some funky power connectors in there for the drives. Likewise the hard drive caddies are weird (and easily the most annoying thing in the machine) and expensive. If you need to pull a drive, you need to pull out the server.
These are the newer model from the one I have. You need a special cable to plug a monitor into it to do the initial setup of the ILOM module. I *think* the cable is the same as the Cisco breakout cable for their servers. Or get a half height video card, that can also work. Or maybe use a serial cable.