As a professional ragtime musician, I checked both takes of the USMC Band, and the way to check speed change is to go from the end of the recording straight back to the start. The difference in pitch is miniscule. I don't know what others have heard. The third strain of the rag goes to the sub-dominant [in the piano version, from Ab to Eb], but returns to the original key at the end, making a direct comparison possible.
