Mijin is getting testing from quite a few large organizations at industrial scale.  This kind of rigoruous third party testing, and the development of resources will make the NEM public chain a great option for smaller operations that aren't moving hundreds of millions of dollars.  They get the same security and access to resources using the same API set, but have a chain with $0 start up costs on their part.

Mijin is good for large organizations that want to do millions of transactions a day and don't want to pay a fee for each one, but instead are willing to invest in serious start up costs. 
NEM won't have those high start up costs and so therefor will be much easier for smaller organizations to build on.