I had one of them, it was my first electronic marker. There one of the lightest markers available.
You don't need an electronic hopper, but you won't get the full use out of it without an electronic hopper.
The EROS SE can fire upto 20bps, but you will be lucky to get 5bps with a gravity fed hopper.
Advice: make sure the orange light is NOT on when using it, as that means eyes are turned off, and you will start chopping.