The carbon on the Amira is definitely a harsher ride (though only marginally so, IMO) than the Ruby. If you have decent pavement, I don't think you'll notice. (On the other hand, you're in northern OH, and if it's anything like Cleveland's pavement...) It's also going to be stiffer. I rode the entry-level model because they didn't have anything else in my size. I'm also between sizes in the Amira (51 or 54). The cornering on the Amira is also going to be better, generally speaking, than the Ruby, but it will also feel twitchier if you were to ride them one after the other.

The Ruby would be great for a century. So would the Amira, I think, but a lot of that depends on how comfortable you are.

FWIW, the Amira's on the short list for my next bike. My lower back much prefers a little more stretch.