Yep, already own this one, but the China-type is more like an AK-47 Mag, indeed the Blasterparts-Banana seems to be styled like a M4-Mag.
The biggest advantage in my opinion is, that you don't have to submit your credit card data to China. Wouldn't feel glad about that.
They look cool. The question is: do they work worth a damn?
As I experienced the guys from blasterparts, I can't imagine the will sell a non-working product. As an example, by my expierience, their tuning kits are fitting as lot smoother than most OMW-Kits. And never had any issues about their customer service...