I have a 4 month old and she has been on blue buffalo puppy food for about 3 months and is doing great although she spits out the blue things all over the floor. It's kind of funny. I have a chance to get before grain 2 for the price of 1. I am considering switching because of the great deal. She has had before grain before and really liked it. If I gradually switch her over should she be ok with the switch or should I let a good deal go by? Any input would be great.