Racing flats can help because they're lighter but also because they are so much more flexible. They have a bit of cushionong but it doesn't last very long. Also watch your achilies tendons because these get stretched a bit more in a low profile shoe (thinner midsole).
However for 5K and 10K racing - keen to improve - i'd say go for it. Perhaps try some speedwork in them first.
I have some 3 year old nike zoom, lots of people have got the Nike Mayfly[url] and there is an adidas zero which I have seen about.[/p
I can't recommend the mayfly enough - just putting them on makes me feel faster!
They only last about 100k but £25 still pretty good value for ten 10k races