We use Netapp's E Series 2800's where we have upgraded the controllers to the 5700 versions. We own 5 in total and have not had any major issues with them. Just a the normal drive replacements and an issue with upgrading the code on one of the controllers which was quickly resolved via a support call.
We are running a mix of SSD and hard drives on these. The SSD is used for OS hosting of our MA's, Index cache and DDB. The disks are divided into pools and then presented as RDM targets for primary MA storage.
The reason for the upgrade is because we found the controllers were limiting the throughput of the backups, especially when AUX copies were also running.