Scion's mechanics are lifted whole-cloth from Exalted 2nd Edition. Individual powers are different, but the combat rules are all the same. The biggest difference between the two systems is the inclusion of Epic Attributes in Scion.
In Exalted (which, to be fair, I've never played) your dice pools just get bigger and bigger. My friend Mike (aka "Doomshadow") had a starting character who rolled 27 dice for his big attack - thankfully he could only do it once per fight. I was invited to play in that campaign, and started concepting a character, when Mike told me about that dice pool. It scared me away.
In Scion, Epic Attributes grant automatic successes, and so there's no "need" for ever-increasing dice pools. It's more efficient (in XP) to increase your Epics instead. I strongly suspect that by the time you get to Scion: God (Legend Ratings 9-12) the game will be more or less diceless. Being (or not being) focused in an area will mean a difference of 10 to 30 auto-successes, so your dice pool of 6 to 12 dice (averaging 3 to 6 successes) won't be worth rolling.
This, however, will not hold true for Greek Scions. They have an ability called Arete, which grants ever more increasing dice. I predict the benefits of Arete will be enough to make Greek characters roll frequently, even at Legend 10.
On the other hand, XP costs may get so out of hand that everyone fills in their weak spots instead of focusing at all - which would be a bit of a let down. This would result in die rolls being a big deal even at high-Legend.
There's also a good chance that the disconnect in reality between (what) the rules (encourage PCs to spend points on) and (what) the authors (of the monster section expect when designing challenges) may result in monsters that are utterly focused in the wrong ways. While this was a problem in Hero, and an annoyance in Demigod, I think it may actually be a benefit in God. Innappropriately focused monsters will push that diceless aspect I'm hoping for. Let's hope the authors didn't read complaints on the forum and adjust to match reality.
I have some issues with the implications of High-Legend on the XP system of Scion, which I intend to blog about sometime soon. However, it won't be for a while. My wife gets back from Disney tonight, so I'll be engaging in the time-honored husbandly tradition of scrambling to get everything clean at the last minute, followed by the time-honored couple tradition of being really needy and clingy for the first day she's back. At least I'm honest about it.