I'm going to vote for the mono Eva, I love the little plate, it is a tiny bag after all. I want the DE too but I'd worry about the plate scratching if you're going to toss it in a larger bag. Although for the mono, I'd worry about the vachetta piping.
Now that I think about it, I'm not sure the Eva is a toss in another bag kinda clutch. She's just too fabulous! Maybe the pochette is a better bet. I have a DA that I throw around inside my NF and when I want to wear it crossbody I just take the strap from my mono Eva.