We did mixed feeding with our son from about 2 days old. We used S26 because that was what the hospital had and our son didn't have any issues with it, but my sister said she used Heinz and was happy with it too. Not the gold versions.
I agree that breast feeding is so much easier at night than getting up to warm up bottles. If the baby is crying and crying and breastfeeding is not getting everyone back to bed for sleep though, then it was bottle time in our case. No sleep = insane mummy and that's no good for anyone.
I usually prepared that day's bottles in the morning and then warmed them if we needed them. Eventually DS just drank them cold from the fridge.