I feed about 50% raw, some brown pasta or rice and a small handful of Redmills Racer.
1 thing to remember is that Redmills, Gain etc are cheap dog foods and has poor quality ingredients...that's why i like to give raw beef, rabbit etc.
I can't say whether it has made a difference to my Whippet as he's a timid thing and lazes about all day. He's no world beater when working but is keen and does a decent enough job for me