For those who didn't notice, over on the Genesys forum @Silverfox13 posted the handbook they used at GenCon when they ran the system. You can check that out here . Here's what it says:
Quote...anything that grants defense (no "+" in front of the number) doesn't stack, and anything that adds to defense (a "+" in front of the number), does.
Also, defense always caps at 4. So nobody can have a defense higher than 4.
So armor and cover would grant defense, while the Defensive/Deflection qualities increase defense.