I'm currently using a Synology DS 1513+ with 5x4 TB Seagate NAS HDD. This system is great for archiving and backup usage but it's too slow to use it as a working drive. Therefore I'm gonna substitute it with a Promise Pegasus R6. As far as I read the cheapest possibility to get a 24TB R6 is to buy the R6 with 6TB and buy 6x 4TB disks anywhere else. I just looked at the compatibility page of Promise and found two 4TB drives there. I guess it's not a problem to buy them aftermarket and not directly from Promise? And my other question is if anyone knows if the Seagate NAS HDD 4TB drives work in the Pegasus? They are not listed in the compatibility sheet... if it's not possible I would sell them with the NAS. Thank you in advance.