From testing this, Barrage's stun goes from mag 2 to mag 3 when used with focus, but I wasn't able to determine the scale. It's definitely less than scale 10, though. Since the guaranteed stun property of this focus spender is meant to replace Stun (the power) being removed from the set, it should be a mag 3 scale 10 stun when used with Focus, to match Stun's old numbers.
Now, I don't like the spender being moved from Bone Smasher to Barrage. It means Barrage is no longer a skippable power for a lot of us. Most of the objections to Bone Smasher being the spender were that it couldn't be used as filler when Focus was up and you didn't want to spend it on Bone Smasher. But if all we're after is filler, Barrage is just a better filler power than Bone Smasher, with its shorter recharge and longer activation.
[Bug Report] Total Focus is only playing its hit FX on a hit about half the time.