The Roman Catholic Liturgy and the Anglican Liturgy were not something made up after the schism. They existed in Orthodoxy in the early Church. The Western Rite restored something that was eclipsed and suffered from it's association with the Roman Catholic Church post schism, and in some ways, but less than expected, reflected the Papal errors, the Filioque, and other aberrations. But until Vatican II, it's decay actually suffered very little.
So the Orthodox Western Rite didn't "borrow" these liturgies until it could come up with it's own Western Rite. I can't think of any thing more unorthodox.
Here are some helpful links to the history, restoration and the current happenings in the Western Rite use of the Orthodox Church.
I think you will find them very informative.
If after you have become more familiar with the history and how there is not a discrepancy or theology between the rites, (there were some changes made before they were adopted, and this is not a recent, but happened nearly nearly a hundred years ago.
See "Introduction to the Orthodox Western Rite" at http://westernorthodox.com/westernised
You will find many articles and information there , and hopefully answers to many questions.
Also Father Nicholas Alford's article is very good. "Light from the East's from the West". Find it at http://members.aol.com/FrNicholas/history.htm
The Western Orthodoxy blog is another: http://westernorthodox.blogspot.com/
I found some of the best reading by going to Orthodox Church/Western Rite Websites. You will find a list of those at either of the above links.
Two I like very much are
ST. NICHOLAS ORTHODOX CHURCH http://www.spokaneorthodox.com/
HOLY INCARNATION ORTHODOX CHURCH http://www.holyincarnation.org/
If you have theological concerns, I am sure there are Priests who could help you with those around here. I am new here so I am just getting to know everyone.
I would also be happy to put you in touch with Western Rite Orthodox Priests that I know personally if by a long shot there are not any available right now at this site.
Thank you for your interest and concern in Western Rite. I have attended both extensively and I love them both and find that when our hearts are turned to the Lord, Heaven bends down and touches Earth if we worship Him in Spirit in Truth in the Orthodox Church.
I find that it is more my preparation body and soul before attending Divine Liturgy, and my openness and participation and unity of faith and love with those I am in community with to be have the greatest effect on receiving the Grace God pours out during the liturgy.
And I don't just mean attending vespers, lauds, fasting, but living out my whole life as one unending Liturgy.
In the Mercy of Christ, my only Hope,