The pre-gens I made hold up really well; I've used them now in over 20 games. I've found a few things I'd tweak, however. If you use them, consider the following changes to the General Ability distribution:
Gabriella (thief): Remove 1 point from driving and explosive devices. Add 1 point to Preparedness and Weapons.
Dr. DuBois (assassin): Remove 1 point from Hand to Hand and 2 points from weapons. Add 1 point to Preparedness and 2 points to Sense Trouble.
Hung-Ke (hacker): Remove 1 point from Weapons, add 1 point to Preparedness.
Mace Hunter (con man): Remove 2 points from Disguise, 1 point from Filch and 1 point from Sense Trouble. Add 2 points to Hand-to-Hand and 2 points to Preparedness.
"Ashcan" (wheelman/explosives guy): Remove 2 points from Network. Add 2 points to Weapons.
Persephone (analyst/mastermind): good as is.
I originally made more niche protection than I needed to, limiting the PCs a bit. The above changes make them a little more flexible and balanced without limiting any of their cool stuff.