We have had the pleasure of working on almost all the Dell MD storage array models over the last 15 years.
Our earliest exposure was to a Dell MD1000 disk storage unit with 1G iSCSI interfaces. It was one of the first shared storage arrays we connected to a group of ESXi 4.1 servers and made them a cluster, since then we have touched almost all storage arrays made by Dell.
One of the easiest arrays to setup are the MD3200 arrays, this also includes the arrays that followed. Our preferred configuration model is to divy up each enclosure into multiple disk groups. Depending on the application, we could create several types of RAID groups. For web server usage, 5-8 disk RAID-5 configurations work well.
For high end business applications with heavy disk IO, look at mirrored stripe sets and chain off some slave units using the 12Gb SAS ports on the rear. The more disk groups the more I/O queues and hence better performance in most system designs.
Currently we are installing and configuring ME4 series hardware for a number of clients. ME4012 is a 12 bay unit using 3.5″ disks, the ME4024 is a 24 bay unit with 2.5″ disks and the ME4084 is a massive 5U 84 disk storage unit that can take both sized disks, with 12TB disks being recommended for a File Storage archive solution we are currently working on.