Regarding the testimonies of those who have encountered God outside of Orthodoxy, I will say this. We Orthodox recognize that where ever there is truth, it is Orthodox Truth. We see Truth being Orthodox, but also see Orthodoxy as being the only place that has the fullness of Truth.
As an Orthodox Christian, I would never dare to question whether another person has experienced God. I remember a Christian-Buddhist Dialogue conference I was once participating it, where I came away feeling that two of the Buddhist monks had indeed encountered God, even though they did not believe in a personal God.
St. Paul talked about the ability of some to know God through natural law. I believe this to be true. I have many friends who are non-Orthodox, including the abbot of the local Zen Center, and I never push Orthodoxy on them. The Holy Spirit will draw whom He will draw. When the Russian monks first encountered the natives of Alaska, they never judged them as pagans, but as children of God. They did not assume their totems were idols, nor did they push their faith upon them. They shared their lives with the native peoples, and demonstrated by their love, the truth of Christ, and His Church.
To this day, the Alaskan natives who are Orthodox, will tell you their native religion is Orthodox, because they came to see Orthodoxy as the fulfillment of their religion. No other native peoples in the lower 48 would identify their native religion as Christian, even if they themselves are now Christian.