Basically, e Won was the first hole punching, DIN mounted VPN box that was robust and user friendly for anywhere near a reasonable price. They are proven and I've used them to connect to panels the world over. It got to the point that my previous employer would put in the contracts that the customer could either buy the e Won and connect it to the internet or pay a lot extra for all service calls. I know there are competing products, but I've never used any of them.
If there is a difference between the Stratix 5900 and an e Won besides price (100% chance that the Rockwell product costs considerably more for no reason), it may be that the Stratix 5900 can't do hole punching, which is the whole reason you would put a VPN box in a cabinet to begin with. Hole punching is when the device communicates out to a server, and you communicate to the same server and it acts as a middle man to get you talking to a device without needing to setup routers and firewalls. This is how things like TeamViewer and Join.Me work as well.