There are a few things to consider.
Firstly, although people will tell you garbage collection will work under raid 0 (Even though TRIM will not), I've yet to see anything concrete to suggest that it definitely works. Couple this with the additional unreliability that comes with Raid 0, and I'd say it isn't really worth it.
That said, I wouldn't have said there was a significant enough performance increase going to a C300 to warrant changing.
If it is more space you require, then I'd personally look at the cost of doing either (Selling your hard drive and getting a 128gb C300 vs. buying another 60gb drive) and decide from there.