Originally Posted by
link0
I would hands down go with the carbon...and generally more durable in crashes.
Uhh.. no.
OP: it's really about the ride you want. The Tarmac will be smoother feeling and perhaps have a better strength-to-weight ratio. The Allez will be stiff and durable. The geometry is the same. 'Smartweld' is really just marketing gimmickry, but now the Allez does have nicer-looking smooth welds (a la Cannondale, which some say weakens the frame). Allezs has been raced to victories under Cipollini (2004) and Tarmacs under Boonen (to name a few). Both are proven bikes and you really can't make a bad choice. Ride both and see which calls out to you.
My first race bike was an Allez, and I am building up a 2013 Allez thanks to a sweet deal from my sponsor for as my current race bike. I don't find them to be the most comfortable, but I love the snappy feel and aggressive geometry. Reminds me of my track bike. It is a bit buzzy on rough terrain tho.
To throw a wrench in it - I would also consider a CAAD10 if you're really lusting after the Allez. Also a superb bike. But if the price is the same for either build, and you're not racing, I would go with the Tarmac.