Replacing HDDs with SSDs

Here is a summary of my current system (Yes, I know it's old, but it suites my usage right now):

I know that I need to update the BIOS to be able to use SSDs and to be able to use a GTX1060 (I already have the GTX1060).

I only put media that I am currently using on the Media drive.  I keep all media on separate external drives and copy them to the internal drive as needed and delete them from the internal drives once the project is archived and backed up.

I do not edit 4K.

I use Premiere Pro CC, After Effects CC, Photoshop CC, and occasionally other applications.

I was planning on getting two or three Samsung 850 SATA III Evos:

SAMSUNG 850 EVO-SERIES - 500GB Solid State Drive - Internal, 2.5 in Form Factor, SATA III - MZ-75E500B/AM at TigerDirect…

I have two SATA III connectors and eight SATA II connectors.

Should I do this for two SSDs:

SATA II : OS

SATA III: Media, Project files, Cache

SATA III: Exports

or this:

SATA III: OS

SATA III: Media, Project files, Cache, Exports.

I will keep the Hitachi HDD for backups of projects in progress.