I like to use multiple drives because I feel like there is still a cost in access time to fetch the files so if you have multiples then you can do those fetches simultaneously. To be honest though the access times with controllers etc may be so minimal that in reality it doesn't matter. One way or the other may not be noticeable.

The only time I have really seen it matter is if you are going to put the drives into a raid array. Tomshardware.com did an article recently about raiding older ssd drives vs a larger capacity newer drive that may help. The newer drive actually came out on top. http://www.tomshardware.com/reviews/...ance,2798.html