But let me edit to comment--
Really this depends on the nature of the saga. If your enemies are more mundane, then sure, the Rego guy is rough. The aurum guy is zap-tastic when your enemies are visible.
But there are demons who just jump bodies, ghosts who possess items, a wide variety of mentem options, Crusaders with relics, Fae who maintain external vis and just come back later, dragons with a storm aspect, priests who bring along enough mundane help to simply overwhelm.
So the exercise, while entertaining, just shows how you can create a magus very capable of handling an issue in one way-- killing it. There's a lot more to the world than just trying to obliterate what might be in your way, and when the magus develops a reputation for that method of problem solving, enemies are going to exploit it. ("Immune to metal? Great, let's use bone/antler weapons. He's a corpus specialist? Looks like we send in the trained attack dogs who go crazy at the scent of the caster. He b-zats everything with lightning? Right, then we rain down arrows from the trees.")
So, yeah, you can chase this route, but what we'd also want to see are the accompanying flaws, because I'm going to tailor stories based on those flaws so that there are opportunities to use the powers the magus is good at, but there are appropriate challenges and obstacles, too. This kind of design is fine for saying, "I want to explode things," but it requires the discussion about "So if you want combat to be mostly a non-issue, that means we shift the focus of the game somewhat. What do you prefer the saga's orientation to be?"