Concerns for the Allez:
Will it handle/ride rough on gravel?
I've ridden mine on dirt and some gravel, with the 23mm tires. The packed dirt was fine, the small gravel was fine, but when I'd hit a bigger rock, it felt like the equivalent of rolling your ankle. Maybe the larger tires would be helpful.


Will I be comfortable on slower/scenic rides with my wife (she rides a Trek commuter bike)?
My wife occasionally rides her Schwinn hybrid or Quintana Roo roadbike. I never had a problem riding slow with her. Just don't expect it to be any kind of workout for you. I also used to ride the critical mass ride downtown until some drunk girl crashed me. You can ride it pretty slow if you need to, it wont kill you.

Will this be too much of a "race" bike for endurance rides?
No. It is fine.


Will the caliper style breaks be acceptable on wet weather rides?
Yes. They have always worked fine for me. Just change your riding style when it is wet and allow more time.


Will I notice the carbon fork upgrade in the Sport or Elite model?
I have no idea but if you pay for it, tell everyone it was totally worth it. It will make you feel better.

Will adding a 28c tire make it more of an all around ride?
Probably.


I have had mine almost 6 years and love it. I have ridden it everywhere.