I know little to nothing about eWallets. Generally speaking, I am a Free Software advocate and skeptical about "partially open" platforms. From a security perspective, though, OSS is not, in practice, intrinsically more secure than closed. It's intrinsically more transparent, but that only enhances security if people actively work on it.

(There's data on that somewhere that I cannot find now, but this isn't just me talking out of my butt. :-) )