I'm for 3 or 2. I saw a gorgeous engagement setting when I got engaged (so long ago) and just thought it was overpriced. My jeweler insisted he could find something really close for half the price, it was close and 1/2 the price but I never loved it the same as the original. I wish I had spent the difference, which now seems like nothing to get the original one. If I was dead set on the larger stone, I'd put the extra in, no problem. But honestly I don't think anyone will be able to tell a 2.7 ct ring and a 3.0 carat ring. So that option would work for me too. But consider, if you decide later you want the 3.0, it probably won't fit into the setting, so I guess I'm back to option 3. Who will know unless you tell them...are lips are sealed.