Don't RAID0 different types of SSDs; you ruiin the performance of the sandforce. Keep them separate.
You also lose TRIM support on both by RAIDing them; only on Linux/BSD is there TRIM-on-RAID support, as of yet.
RAID0 generally on SSDs makes sense; SSDs are already using RAID0 internally. The Sandforce has 8 channels and the Indilinx has 4 channels; which could be considered an 8/4-disk RAID0 array that the controller exposes via the SATA interface. SO RAID0 is common, and if you keep a good backup there's nothing wrong in doing so. Especially with Intel drivers you can get a speed boost, by enabling Write Caching option.
But in your case, keep your Sandforce and Indilinx separate; they behave very differently and losing TRIM isn't worth it.