This is something I'd been meaning to do ever since I got Viva La Vespa a few weeks back. A few blogs had mentioned that SD was a little dupey to VLV, but I couldn't find any comp pics. Since I was getting ready to remove my previous nails, I figured I'd do a little swatching before I soaked them off. I'd already used n-a remover on the nails about 2x at this point, and the texture on the SD nails is testament to that, for some reason, they showed it much worse than the VLV nails. So I apologize for the texturing, but at least you can see the difference in the colors.
Viva La Vespa is on index and ring fingers and Sexy Divide is on middle and pinky fingers.
As you can see, while they are similar, I wouldn't call them dupey. More like, Sexy Divide reminds me of Viva La Vespa. Sexy Divide is a gorgeous color in it's own, though I think I prefer VLV. I'd say that Sexy Divide is a true Tyrian/Imperial purple (though looking up colors on Wikipedia has led me to think this is actually Byzantium purple, but that's so random). VLV is in the same family, but it leans more magenta. Also, SD is nowhere near as glowy as VLV. VLV has the same quality as OPI Kinky in Helsinki in that it looks like it's lit from within.
In terms of application, SD was far superior. The pic is 2 coats of SD and it was opaque at one. I just did 2 to reach bottle color. As for VLV, as I mentioned in my previous post, VLV is thin and a little difficult to work with. It also took 3 coats to reach the above color and there is still a bald spot on my ring finger. I suppose that's the difference between new formula (SD) and old formula (VLV).
If you are lemming VLV, but can't find it, then I say SD should help to calm your lemming. It's not a dupe, but it's in the same purple family and is amazing in it's own right. However, if you can find it (as far as I know, VNS still has it), VLV is a must have for any purple-ite.