I'd love you to become OO, and I think you should.
Your zeal for making converts to the Oriental Orthodox Church is much appreciated, but please try to remember that we have rules against proselytizing.
I am actually not too familiar with the prayer written by Catholicos Simeon, but he is respected as a great catholicos (among other things, he introduced the first printing press in Etchmiadzin) and I have never heard him criticised. In fact the sentiments expressed in his prayer are quite consistent with how the Armenian Orthodox regard the Mother of God. She is the most honored and beloved saint in the Church. Why shouldn't she be, when it was through her consent to the Angel Gabriel that our Savior came into the world? Her intercession is sought more than once during the Sunday liturgies and on certain feast days, hymns are sung which honor her:
"O Mother of God, tabernacle of the light of the unbounded sun of life, thou didst become the dayspring of the sun of righteousness and didst shed forth light on those who sit in darkness; wherefor we all praise thee always.
"O thou undefiled temple and burning bush who art not consumed, thou didst bear in thee the fire of the Godhead that is not burnt, wherewith the flame of the passions of our nature was burnt and consumed; wherefore we all praise thee always.
"O thou living ark of the tables of the testament of the new covenant, through thee was cast up the way to the land of the promise, the Word that was fashioned in thee by the Spirit; wherefor we all praise thee always."
From another hymn:
"Thou gem-like rose of unique color,
Thou golden peacock,
Thou gem-like rose of unique color,
Thou moon of the Sun
Full of light in the night
Thou Saturn, resplendent in the morning!"
I have never heard that there was a difference between our Mariology and that of the EO's. I always thought our regard for her was the same.
We really love her. I think one reason is because her own love for Christ is so strong and unique. When you think about it, we love Christ for purely selfish reasons, because He saved us. The Mother of God, on the other hand, loves Christ no matter what, because He is her Son. She would love Him regardless of whether He saved her or not. Her love is the strongest of all human love--a mother's love. That is why she is such a strong intercessor. She loves Christ so much and has such a unique and loving relationship with Him.