Pochette! I have the smaller one and I love it. I think the bigger one is too big to use for inside a regular size bag. Plus I love the chain on the smaller one. When I travel, I hook it inside another bag and put the very important things in there like my IDs, extra cash, etc. I think overall it's more fuctional than the ZCP. U can still put cash and cards in it. And even some make up... I'm small so I even use it as a clutch by itself too!! The ZCP in Red vernis is going to be my next purchase tho!!!
I think you should get the pochette accessories, because you can use it inside your speedy and also alone as a separate purse. But make sure to get the full size pochette and not the mini because it is only $85 more.