This reminds me of an album put out a few years ago by Passion: Hymns Ancient and Modern
. I was at a Chris Tomlin show and he mentioned that he had a few songs on there where he and other bands (Dave Crowder included) had recorded some ancient hymns with a full band. It turns out that, barring the Doxology and Phos Hilarion, the "ancient" hymns were mostly from the last 100 years.
By the way, the introduction he gave at the concert to the Phos Hilarion was to say that in the ancient church, the Phos Hilarion was chanted instead of sung so he had the crowd "chant" it by reading the words off a powerpoint screen.
The track list to the CD:
1. O Worship the King
3. Joyful, Joyful, We Adore Thee
4. Praise the Lord, the Almighty
5. Father Let Me Dedicate
6. How Great Thou Art
7. Raise Up the Crown (All Hail the Power of Jesus' Name)
8. All Creatures of Our God and King
9. The Solid Rock (On Christ the Solid Rock)
10. Phos Hilarion (Hail Gladdening Light)
11. Joyous Light
12. Here is Love
13. Fairest Lord Jesus
14. Take My Life
Like you said, hopefully they'll be led back to Holy Orthodoxy.