Too bad that Promise has fouled things up by restricting the drive options for the enclosure.
Would there be a noticeable difference in performance between Pegasus2 and a comparable USB3 external drive solution (assuming hard drives, not SSDs) hooked to the nMP?
The compatibility list can be found here: http://www.promise.com/media_bank/Download%20Bank/Compatibility/Pegasus2_Compatibility%20List%20v1.1-201301216.pdf
Note the difference with the Promise Pegasus2 diskless model and the model that ships with disks installed. They are not the same.