I made this today using 60g of home made Greek style yoghurt instead of vanilla, plus added ¼ tsp ground cinnamon. Really enjoyed the flavour of this and it wasn't too tart either. It's very similar to the normal banana smoothie I make (but that doesn't have yoghurt added), but this was nice on a cold morning. Will make again.
Edited to add: I could only drink ½ of this before I felt very full. I've covered the remaining and will have tomorrow. It's amazing how when the oats are cooked and it thickens the mixture it makes it more filling than just having a normal smoothie.