Edge is a superpower and don't let anyone tell you differently. I think an unaugmented human with Edge 7 or 8 is highly viable.
That said, Edge is a superpower that plays out differently at each table. At a table which focuses more on the narrative and doesn't roll a lot of dice, or at a table with regular Edge refreshing, with Edge 7+ you can Edge just about every single roll you make during a session. That's powerful.
If you play at a table with long, running gun battles with lots of combat turns and lots or rolling, or where Edge doesn't refresh very often, then Edge 7+ is still potent but you have to be more selective about its use.
In my experience, Edge can be especially potent for Faces, who often have a few key rolls over the course of an adventure (the negotiation roll, maybe an etiquette roll, maybe a con roll), so it's easier for them to know when to apply Edge to its maximum effect. Then, during combat, they can use Blitz, which gives them a 90% shot at three initiative passes and an outside shot (~10%) a fourth pass depending on their REA+INT and how well they roll. That's more than enough to let them 1) act first, 2) use full defense if they get attacked (along with Too Pretty to Hit) to stay alive, and 3) have plenty of passes to either attack or use Leadership on their teammates. Suppressive fire can be hugely valuable, even with a relatively modest dice pool. It's more of a support role in combat, but still very helpful to the overall effort.
