There is No way to know if a bike fits you without sitting on it. I use the Competitive Cyclist fit-meter, but still .... I have to actually draw a picture in side elevation of any proposed new frame and then draw a picture of myself---my proportions as measured---to figure out how things might fit (and it has been pretty accurate so far,) But everyone has different proportions .... everybody tells me I need a 58 or 60-cm frame but I usually fit better on a 56 because of my proportions and certain flexibility issues.
If you can spend $2500 on a bike you want to keep for ten years, you can spend $100 to rent a car for the weekend and visit some bike shops for some test rides.
I checked out the Defy a while back---it is a great bike. i think ti fits 30s or 32s, which isn't enough for real dirt, but should be fine for mild off-roading on hard packed-earth roads. Probably someone who owns a modern version can tell you what tires actually fit.
I went with a Fuji Sportif---but they make a CF version called the Gran Fondo or gran Fondo Classico---they used to be every bit as good as the rest but cheaper, but it seems their prices might have gone up.
As for the Defy, I was very close to buying one, so I can sort of recommend it.