if i want to go 100% s&p 500, through fidelity... is fxaix (for roth) and voo (for brokerage) the recommended setup?

my understanding is fxaix is best for roth because it's a tax advantaged account, and the expense ratio (0.015%) is lower than voo (0.03%)... and voo is best for a taxable brokerage because it's transferrable, should i ever wish to move away from fidelity. is this accurate? or should i go with the same thing for both, whether that's fxaix or voo? (roth ira is at $25k and brokerage will be starting with $400k, if this is relevant. employer 401k is mmwvt, $420k, through merrill lynch. will not be