Hello. Nice comparison.
I´d correct the conclusion a bit. It might be nit picking or rhetorics, but it is very important in real life: Noise amount, and noise performance are two very different things. And I believe 70D gains another stop here, because the noise is better, easier to clean up. And that makes closer to two stops overall, which means lowering the final output noise to 25% of 350D. Sounds fair to me. But we are on the edge of fall. You might consider Canon made 3,5 stops of imrovement two months later, and that is not bad at all. No car models goes 3x faster, no sportsman runs 3x fater or throws 3x further, no thing will make you 3x happier if you´re already happy.
But Intel did it, and Canon did it too!
And then in this lazy sunny day we put half empty beer bottle on the table, clean our beards and say "Nah, not enaugh Canon, not enaugh!" :-D
P.S.: Take it with ease, I wanted to make it fun.