Hi Paul and Belinda
Given the option, I would go for the biggest system, ie the 400 amp system, you can afford. The reason we didn't go with EV Power is the distance from Brisbane.
There is no use spending big money on a system that 'might do' compared to a lithium battery system what 'will do'. Considering your family of six, go for system more than what your current needs are (children grow and does their screen time) and what you can afford. I feel that if you go with a 300 amp system system, and with a family of 6, you maybe at the limits of the system, and that would defeat the object of want you want to achieve. The simple fact is, the more power you have, the more you use, and with a family of 6 you would more than the two of us.
The Enerdrive people do put out a good system, that is why Kedron are using it. Why not contact Springers Solar at Capalaba for a quote,
Cheers
Peter