Best use of battery backup

[Fence13]

So I'm setting up a new tank and I'm trying to figure out the best use of my ecotech battery backup. Tank will be about 66g.

Do I use it in the return pump or the powerheads?

Was thinking two options:
Vectra S1 with the backup
Then gyre or tunze for flow

-or-
Varios return pump
MP40QDw for flow with battery backup

Thoughts?

 

[Fence13]

I want to add that I already own this ecotech battery.

 

[landlubber]

personally I would prefer the return pump to be covered. this ensures the whole system is turned over as opposed to the sump sitting idle, even more important if you keep live rock or any media that encourages bacteria population colonization as that is what you're trying to keep alive.
either way I think having that insurance either with the powerheads or return pump will take your tank a lot further.