Power to VLIO on 9P_9215

The manual says that VLIO can optionally be connected to a 5V supply, and implies that this is preferable for efficiency in mobile applications. However I didn’t find any indication of the likely power saving.

I have +5V regulated available, and am generating 3.3V off this, using a small POL converter.

I am therefore minded to connect VLIO to +5V - are there any drawbacks anyone knows of?

Also, in different places the manual implies that the upper limit of VLIO may be 5.5V or 5.0V - which is right?