It can't.
You can either have the percentage reading or get rid of it. There is no middle ground, I'm afraid.
Personally, I could not go back to playing it any other way. It adds that little element called 'Doubt'..
I'm proper scared of Destroyers now as well.
Actually, I think it is very much possible to make an estimate of the amount of damage you have taken without any read out what so ever. It does take a little bit of experience but once you start thinking about it, it's fine.
There are only two damage levels you need to be aware of any way "Good to Go," and "Oh God, we're screwed..."
