The LSI MegaRAID SAS 8708EM2 RAID-controller is very good at reading. It prefers heavy loads and arrays with quite a lot of disks. It is very effective in choosing what disk in a mirror pair will take less time to access the required data. It is also good at reading from degraded arrays: its processor is fast enough to achieve a high speed even from a RAID6 with two failed disks. Multithreaded reading is fast on this controller, too.
Writing is, on the contrary, the weak point of the LSI MegaRAID SAS 8708EM2 due to the small amount of cache memory or firmware flaws. This controller won’t be a good choice if your applications do a lot of writing.