Moving User Folders to an External Raid 5 Array

I have a 2011 27" iMac with an internal 2TB HDD.

I have already added an internal SSD and made it my boot and system drive.

I have kept all the user folders on the original HDD which is now getting full and slow.

I'd like to use an external TB Raid5 array for my user folders and their data, moving all the user folders/data from the internal HDD and re pointing to OS to the new location for the users folders. I will then stop using the internal HDD. The Boot drive stays on the SSD.

Any reason this should not work/or problems I may face?

The only issue I see is potential spinup time for the external array v. the internal drive.

Considering LaCie 5big or Promise Pegasus arrays.

Thanks

db