Neither of the links listed a weight, so we don't know if it is lighter. The epi-pen is not all that heavy.
The form factor looks convenient, it would certainly go into a pocket better.
The current generation of epi-pens contains two doses of epi. This device doesn't say how many doses it contains. This is quite important, particularly in a wilderness setting. As a health-care provider who does not have any serious allergies I prefer to carry a vial with at least four doses of epi and a couple of syringes. I might not feel that way if I thought I would have to inject myself.