There are apparently - though I wasn't aware of them until recently - comercial food is digested more quickly (4 hours ish) while raw takes up to 12 hours to be digested - so feed the commercial in the morning and then the raw after 4 hours and you should be fine. Having said that - if a cat hunts and eats 'natural' raw (i.e a mouse) and then comes inside to eat commercial food what then? So I am personally of the opinion it can't be too bad to just feed what you have when you have it, sometimes mine turn their noses up at raw or wet and I end up giving them the other. I've tried to stick to a routine - wet in the morning (for those being fussy) and then raw later on, but often I find I don't stick to it - the intent is to go onto 90% raw if I ever get my act together enough to defrost it at the right time!
and when Minnii decides she likes it enough to eat every day!