SSD option for setup, game performance NOT OS

[OSMMORPG]

I have looked around the net for this info, but was not able to find too much.

Correct me if I am wrong.
Level 1, Having two HDD installed, with OS on one and Game files on other. Is the first step to faster game play. Compared to just having OS and game on one drive.

Level 2 skills. Having two HDD with a RAID 1 set up. "Increased read performance occurs when using a multi-threaded operating system that supports split seeks"

Level 4 SSD

So lets go think what fit in level 3?
I was wondering if it worth going to the trouble of setting up one HDD and a smaller 30gb SSD for game files only (cheap $50 investment). Let say WOW, FFXIV, or any game. Since the OS is still on a normal HDD, would it limit/hurt the SSD performance FOR GAME vs game+OS on SSD. If it does how much?

Let say on a 1 to 10 scale. 10 being SSD performance 1 being HDD performance. Would installing the game and playing it on this set up be 7/8/9?
Or instead since HDD OS is limiting everything, it might bring us back to 4/5/6?

I understand that OS performance will be the same, but my main focuses is for the game performance. Since we load textures from the drive each time we spam a spell or zone.

Seagate Momentus XT 500GB Hybrid, is really not an option for level 3. Since cost wise for $100, there are much better option.

 

[Twoboxer]

You'd get some gains, but I'd guess you'd give some back to being bottlenecked by the OS.

I suppose you could try it to see if it improves loads and hitching, and worst case add a second one for the OS if it doesn't.