The cost of a 500gb is cheaper then 2x 250gb and almost half the cost of 4x 120 gb
It has been shown numerous times on this forum and others that there is not much to gain from SSD drive in raid.
Add in the fact that in RAID O if one drive fails or has any data loss you are hosed.
Don't worry about price I can get any of those
Just tell me when config is faster
http://www.tomshardware.com/reviews/ssd-raid-benchmark,3485-11.html
"Our third real-world benchmark provides us with pretty much the same results as the first two. There’s practically no difference between the SSD-based setups, whether you're looking at a single drive or two in RAID 0. In this one, we're booting Widows 8, starting Adobe Photoshop CS6, and loading a picture."
Well, now that we've done your research for you, showing you that you won't see any real benefit, and laying out some of the downsides...you seem compelled to want other data that supports your presupposition that a RAID 0 will be 'faster'.
Of course, you haven't said 'what' you are copying, to or from what other device, or how much data you may be copying.
You asked: "what should i do"
I suggest you go do your own research, and find some data that supports your preconceptions.
Then go do whatever it says.