1 512mb is better
They compared RAID0 128gb vs 256gb, but it's the same basic idea
One SSD on its own scores again in the contrived tests we put together. The performance differences when we boot up and shut down Windows 8, then fire up different applications, are marginal at best and not noticeable in practice. Single drives actually manage to outperform the striped arrays some of the time, even.
If you're planning an upgrade and want to know whether to buy a couple of 128 GB drives and put them in RAID 0 or just grab a single 256 GB SSD, for example, the answer still seems clear enough to us: just grab the large drive and use one. Using Samsung's 840 Pros as an example, a pair of 128 GB drives will run you $300 on Newegg right now. The 256 GB model sells for $240 (maybe that's why it's out of stock currently). There's also the issue of reliability. If one drive in a RAID 0 configuration fails, the entire array is lost. At least for a primary system drive, one SSD on its own is safer.