We are looking to build private blockchain on Substrate. It should be scalable up to 300 validators. Like start with 3 and scale it to 300 later on. Does standard AURA suitable for this? Can AURA handle 300 validators without any problems? Or should we integrate Staking pallet instead?
AURA determines the next block author from a given set of validators. The staking pallet is used to manage funds at stake by network maintainers.
They can be used in correlation; AURA determines the next block author from a given set of validators, this set can be chosen based on the amount of funds at stake by network maintainers.
But to answer your question, I don't see a reason why you can't use AURA for a set of 300 validators.