A 30kWh “superior” battery won’t be a match for a 45kWh inferior battery, not as Fogstar are inferior anyway but, you get my drift. “Superior” could also mean the installer gets a better discount on certain brands!
Fogstar are decent batteries for the right price and have full traceability where there from, who there from and all the info, which is more than you can say about the more well known brands.
If I were you, I would stick to my guns and make sure an order is put in for what you want!
Are you going for the fogstar rack system?