Help me decide on aluminum/carbon tradeoffs

In article
,
wrote:

I am looking at buying either the 2008 or 2009 Specialized Roubaix.
2008 has carbon fork, rear stays, and seat tube. 2009 is all carbon.
I can get 2008 for about $1400. I can get 2009 for about $1800. $400
extra for the all-carbon frame.

I'm a pretty casual rider. No racing. Usually do 20-30 mile rides
2-3 times/week during the summer months. All told, no more than 1000
miles/year.

$1800 seems like a LOT of money for a bike. Well so does $1400, but
my cheaper alternative is the $1250 Trek 2.1 which has Tiagra
components. Friend talked me into a 105-class bike and the Roubaix
feels good.

Any thoughts if I would be foolish not to eak out the extra $400 for
an all-carbon bike? I'm sure the carbon makes a difference for 50-
mile rides, but I'd maybe do one of two of those a year.

I currently ride an aluminum bike w/ steel fork. Frame doesn't quite
fit right and RSX STI shifter is worn out.

Might as well get any of those bicycles except for one thing.
Your current bicycle does not fit you, and you do not know why.
Best you find how to fit yourself with a bicycle before spending
money that you do not want to misspend.

--
Michael Press