I have an A1 Aluminum Secteur Elite and coulnd't be more happy with it, don't know how it compares to carbon though.
At that price point you're looking at a mid high end bike where in my opinion the next step up won't be a huge jump in noticeable quality. For example you may get something that's x amount % more compliant but the % is so small it will be hardly noticeable unless you're an elite racer and every second counts.
Same thing goes for components, the 105 may switch gears .6 seconds faster than a Tiagra but the real question to you is if that's going to make a difference in your performance based on your personal needs.