Hi Colin.
We feed raw, as do what I think is an increasing number these days. When we switched from (many years of) kibble, all our dogs' health, condition, digestion improved immediately. (They don't need a "balanced diet" with fruit and veg etc; they're not humans; they just need the right proportion of mixed meat, bone and offal).
However, the great majority of the wonderful Champion and Ftch dogs you see are fed purely on kibble. It's certainly not doing your pup any terrible harm.
So leave them on that for now, sticking with the brand for now that you got from your breeder, and in the meantime read up on raw feeding. It's actually very easy, but you need to know what's involved and some basic principles before you start.
Don't mix and match, particularly with young puppies. Just leave them as they are for now and look into raw (the raw feeding Facebook group has some useful stickies
https://www.facebook.com/groups/rawfeedinguk/).