Anyone know about RAIDs?

Those are only the maximum theoretical numbers a given server can have because they don't oversell. When you buy a VPS from them you can upgrade as your needs change. They also have to reserve a significant amount of RAM for shared memory, etc.

Edit: I know from conversation that the average number of VPSes per server is around 30.

 

Sounds right, but they could have taken the opportunity to say that those were max numbers and they never over sell where they listed the number of vps containers per node.