Dear ByzantineAscetic,
ALL Grace comes to us from the God-Man Jesus Christ.
As St Paul says, Salvation is through the Man Jesus Christ or through His Deified Humanity.
Unless one believes that Grace under the New Covenant can come from someone else OTHER than OLGS Jesus Christ, there should be no problem in agreeing that just as Christ came to us through the Mother of God, so too His Grace comes to us through Her intercession and that of all the Saints.
If any Orthodox disagree with this, they are saying so because they are trying to be different from perceived Catholic teaching for the sake of being different.
Something similar happened when certain Orthodox denied Orthodoxy believed in Mary's Holy Conception and Assumption in Heaven - after these were defined by Rome.
It's a good thing Rome has never felt it necessary to proclaim the dogma of the Trinity infallibly. I wonder what some Orthodox would say then . . .
But, really, don't accept what some Orthodox say or write as representative of all of Orthodoxy.
Alex