Since you mention
Dr. George E. Ladd, I thought I'd place this video link here (video by Dr. David Hocking)
because Hocking mentions a quote by Ladd, as part of Hocking's message here about the wording of Revelation 5:9 (said by the "24 elders") and the manuscript evidence available on Revelation 5:
...approx. 9-min vid of
David Hocking on the text of Revelation 5, especially v.9...
and the manuscript evidence showing this:
--
"Of the 24 manuscripts available on Revelation 5... 23 of them have verse 9 saying "US" ['hast redeemed US'], whereas the other [1] manuscript leaves it blank/untranslated" (somewhere around the 3:30-min mark);
--within the first few mins of the video, Hocking tells what
George Eldon Ladd says, "in his book,"
about Rev5:9 and what the "24 elders" are saying there, where Hocking quotes from Ladd's book (I assume from Ladd's
book, not his commentary):
Ladd on verse 9 - "If in fact it is 'us,' then that group is speaking about their own redemption, and must refer to the church"
Then there's this...
George Eldon Ladd, in his book A Commentary on the Revelation of John, says:
"This is very important for determining the identity of the elders. If the King James Version is right, the elders are identified with the redeemed, [...]"
____________
... and then another point by a
different author (M. Svigel, I think??):
"34 Mounce, Revelation, 121, takes the third person plural in Revelation 5:9-10 as proof that the twenty-four elders are not the Church, since the saints would not sing about others if they meant themselves. However, the object of worship is God, and the singing of praises to God with the objects of his mercies in the third person is not unheard of in ancient hymnody (cf. Ps 112; 114; 127)."
____________
... another point made by others is, though v.5 DOES say "US," that even if v.9 says "THEM" (there's actually variants on *this* verse), it could still be reasonably explained by the concept of "antiphonal singing,"... especially as we do see more voices ADDED the further down in the passage we read.