Augmentation and diminution - not only factors of 2.
The current feature of Paste in Double or Half duration allows the creation of canons with augmentation etc.
However, I wonder why this has to be restricted to powers of 2. Admittedly few composers have used really unusual factors, but it seems to me that maybe allowing factors of 3,5,7 and 11 might not be totally worthless.
Probably not a very high priority, but could be nice to have.