I have two children who would fall in the very broad definition of G and T and even I don't think they should be taken out to have one to ones with anyone!
They just haven't reached this ceiling effect whereby everything is too easy for them at either of the primary schools they have attended. This may apply more in maths, but in literacy- surely if they are given differentiated comprehension, the opportunity to read way above their age (in graded ways, not just as free readers) then if they want to write, they can write pages of great writing, they are free to do that. They are hardly inhibited by anyone else not being able to do that, in the way that a child who is very poor at reading and writing often does become completely discouraged when they compare themselves with others.
Or perhaps they are not exceptionally bright, but they always seem to find things to interest them, their own projects, ideas, stuff to make, games to play- to me that's part of being a bright child, intense curiosity about the world.
I was super-bright but wasn't massively academically challenged til about sixth form, but I have to say I also didn't try very hard in subjects I wasn't naturally good at, and if there could be one amendment to teaching brighter kids, its to let them know how to learn/motivation even when it isn't in a subject which is natural to them.
Otherwise, I think being able to read is an absolute gift in life. If you look at the reading level of the prison population, about 50% can't read or write very well. I would rather get the general levels of literacy up with any spare money we had, through intensive intervention very early on in primary, than worry about pushing the really bright kids just that tiny bit more. In terms of making a difference to life chances, I firmly believe that is the key one.