I like to buy primers at least 20,000 at a time, making sure they are all the same lot #. That gives me a batch of ammo with one less variable to contend with.
Sometimes I have to change brands because my favourite primer (Federal Match) is not available in a large quantity. When changing to Winchester, for example, in a 308 match load, we had to drop the powder charge about a half grain to keep the same velocity.
I have never seen much of a pressure/velocity change between primers. HOWEVER, I have found that ball powder, especially with a light load with a light bullet is hard to ignite. In that situation, regardless of caliber, I use only a Winchester primer or a Magnum primer.