I test rode the Infinito CV and found it to have a nice, smooth ride. I also noticed that it felt heavy. Sounds like you've already got a *****in' group, wheels, and cockpit, so not a lot of opportunity to lighten things up without dropping tons of money. So why don't you sell your frame and buy Bianchi's new Specialissima? It's got the same countervail tech for a smooth ride, but is lighter than the Infinito. Just a thought.
I personally don't have any experience with the other two frames you mentioned, but can say that if I were in your shoes, I wouldn't be getting rid of that Bianchi for either of those two bikes.
For what it's worth, I've got two bikes: a 15-pound Emonda SL8 Red and a ~21 lb. steel Trek 420 I converted to fixed gear. For moderate sustained climbs, I tend to have the same average speed and in some instances am faster on my 420. On any given day, I tend to have a slightly higher average speed on my 420. That could be due to it being fixed gear and I'm pushing myself harder.
The point is, though, that the 6 pound difference between the two bikes doesn't negatively impact my performance. To be frank, you're simply not going to get a bike that's 6 pounds lighter than your Bianchi, unless you drop $15k on an Emonda SLR10. So what you're talking about is a weight savings that will be significantly less than 6 pounds. And if 6 pounds doesn't make a difference, you can bet something less than that won't either.
If you want a lighter bike just to have a lighter bike, that's totally fine. I just think you're fooling yourself if you think a lighter bike is going to improve your performance any.