Yes! Transpose by octave would be really handy.
Other units would be cool too. Might as well have them all!
Minor 2nd (Semitone)
Major 2nd
Minor 3rd
Major 3rd
Perfect Fourth
Tritone
Perfect 5th
Minor 6th
Major 6th
Minor 7th
Major 7th
Octave
(List taken from Myriad’s (audio file batch processor) Transpose action.