Hi,
What I've read is that it was a "harmonizer", which could also refer to the H949 (which Laurie owned as well). If you have a link to articles referencing it being an H910, I'd be interested to read those.
This effect is almost certainly the "Repeat" feature of the H949, which repeats the last 400ms of audio while it is engaged. The "O Superman" tempo is about 150bpm, at which a quarter note is 400ms. Given that the "Ha" repeats on the quarter note, this seems to point towards the "Repeat" feature.
In fact, the H910 only has 113.5ms of delay, so even with Feedback at 100% (to get a faux-looping sound), it wouldn't have enough delay to make this possible.
This is all pure speculation, of course, but seems likely to be the H949.
-Tom
