You would probably get the standard Raid-0 Benefit, I don't know if algrorthym that the Drive uses to decide what to put on the SSD part of drive would know what to do. If it works things that get stored should run faster.
Seagate does not recommend using them in raid. If you use them in a hardware raid APM keeps spinning down the drives and yo have to wait for them to spin back up often. This leads to many lag spike. Software raid (win7, linux) will allow you to turn off APM but the result is slower drive performance than a hardware solution. I dont beleive any firmware has been released that resolves the issue with hardware raid, Seagate naturally says to use their ES line.